IT Certification & Interview Help.

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CCNP Based INTERVIEW QUESTIONS Part 8
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SWITCHING
What are three types of LAN traffic?
Unicasts - intended for one host.
Broadcasts - intended for everyone.
Multicasts - intended for a only a subset or group within an entire network.

What are unicast frames?
Unicast frames are the most common type of network traffic. A unicast frame is a frame intended for only one host. The only station that processes this frame is one station that has its own MAC address in the destination portion of packet.

What are broadcast frames?
Broadcast frames are frames intended for everyone. Stations view broadcast frames as public service announcements. All stations receive and process broadcast frames. In large networks, broadcasts can cause serious performance degradation in network hosts - (broadcast storm).
The destination address of broadcast frames (Data Link / Layer 2 broadcast addresses is FF-FF-FF-FF-FF-FF or alternatively all 1s in binary (11111111).

What are multicast frames?
Multicast frames address a group of devices that have a common interest. These frames allow the source to send only one copy of the frame on the network even though it is intended for several stations. Only stations that have a card that is configured by software to receive multicast frames for a particular multicast group can process a frame to that multicast address - all other stations discard multicast frames
What three major functions do Data Link Layer / Layer 2 Switches perform?
Address learning
Packet forwarding/filtering
Loop avoidance by spanning tree

What will occur when you attempt to segment a network with hubs and repeaters?
Basically, hubs and repeaters become extensions of the physical cable plant. All devices that connect to either a hub or a repeater share the same bandwidth and by definition hubs and repeaters create a single broadcast and collision domain.
Think of both devices are pass-through devices much like a electrical power-strip. Hubs and repeaters reside on the Physical Layer / Layer 1 of the OSI model where they pass 0s and 1s along the wire or up to the Data Link Layer. CSUs / Channel Service Units fall into the same category. All are regarded as unintelligent devices. No addressing takes place on the Physical layer.
What three devices are used to segment a LAN?
Router - logical addressing - IP address
Switch - physical addressing - MAC address
Bridge - physical addressing - MAC addres

What is microsegmentation?
Each workstation or network device on the network has its own dedicated segment - also known as a Collision Domain - to a switch. Each device gets the segments full bandwidth and does not have to share the dedicated segment with other devices. Collisions are reduced because each segment is its own Collision Domain.
Important: Full-duplex transmission is achieved by microsegmentation. Each device can send and receive at the same time which doubles the amount of bandwidth between nodes.
What are the three switching methods in Cisco Catalyst switches?
The three frame operating modes to handle frame switching are
Store-and-forward
Cut-through
Fragment-free

What is the Cisco Catalyst store-and-forward switching method?
In the store-and-forward switching method, the switch receives the entire frame before it forwards it. The switch reads the cyclic redundancy check (CRC) to make sure the frame is not bad. If the frame is good, the switch forwards it. Because the switch stores the frame before forwarding it, latency is introduced in the switch. Latency through the switch varies with the size of the frame.

What is the Cisco Catalyst cut-through switching method?
In cut-through switching mode, the switch only checks the frame's destination address and immediately begins forwarding the frame out the appropriate port. Because the switch checks the destination address in only the header and not the entire frame, the switch forwards a collision frame or a frame that has a bad CRC.

What is the Cisco Catalyst fragment-free switching method?
Also known as modified cut-through, fragment-free switching checks the first 64 bytes before forwarding the frame. Ethernet specifications state that collisions should be detected during the first 64 bytes of the frame. By reading the first 64 bytes of the frame, the switch can filter most collisions, although late collisions are still possible.


What is the default switching mode in Cisco Catalyst 1900 switches?
The default switching mode for the Catalyst 1900 is fragment-free.

What is half-duplex transmission mode?
Half-duplex transmission is the default mode that Ethernet functions in. In half-duplex transmission, a device can only send or receive--not do both at once. In half-duplex mode, stations are susceptible to collisions, and efficiency is rated at 50 to 60 percent.
What is full-duplex transmission mode?
In full-duplex mode, a station can send and receive at the same time. In full-duplex mode, collision detection is disabled. This mode offers 100 percent efficiency in both directions.
On a Cisco Catalyst 1900 switch, what are the default duplex settings for 10BaseT/100BaseT ports, default switching mode, and default protocols?

What are dynamic addresses on a Catalyst switch?
Dynamic addresses are addresses that the switch learns about dynamically through the learning process. If the switch does not see a MAC address for a certain amount of time, it drops the MAC address.


What are permanent MAC addresses on a Catalyst switch?
Permanent MAC addresses are entered manually by the administrator and are not aged out.

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CCNP Based INTERVIEW QUESTIONS Part 7
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ROUTING
How do OSPF-enabled routers build adjacencies and exchange their routing tables?
OSPF-enabled routers build adjacencies by sending Hello packets out through all OSPF-enabled interfaces.

If these routers share a command link and agree on parameters set within their Hello packets then they become neighbors. If these parameters differ then the routers do not become neighbors and communication stops.
OSPF routers form adjacencies with certain routers. These routers are determined by the layer 2 (data link) media type and as soon as the adjacencies are formed each router sends LSAs (Link State Advertisements) to all adjacent routers. The LSAs describe the state of each router's links. There are multiple LSA types and a route that receives an LSA from a neighbor records the LSA in a link-state database and floods a copy of the LSA to all its other neighbors.
When all databases are complete - then each router uses the SPF (Shortest-Path First) algorithm to calculate a loop-free topology and builds its routing table based on this topology.
It is important to note that the Hello protocol is bidrectional and is the means by which neighbors are discovered and acts as keepalives between neighboring routers. It also establishes and maintain neighbor relationships and elects the DR (Designated Router) and BDR (Backup Designated Router) to represent the segment on Broadcast and NBMA (nobroadcast multiaccess) networks.
Note: Hello protocols are sent periodically sent out each OSPF-enabled interface using IP multicast address 224.0.0.5. The default interval on NBMA (nonbroadcast multiaccess) networks is 30 seconds. The default interval on Broadcast, Point-to-point, and point-to-multipoint networks is 10 seconds.

What are LSAs (link-state advertisements)?
LSAs are sent out all OSPF-enabled router interfaces describing the state of the router's links. They are also packets that OSPF uses to advertise changes in the condition of a link or other OSPF routers.

Name two LSA (link-state advertisement) types?
Type 1 LSAs are router LSAs and are generated by each router for the area to which the router belongs. These LSAs describe the states of the router'links to the area (area 0 for example) and are flooded within a single area (area 0 for example).
Type 2 LSAs are network LSAs and are generated by the DR (Designated Router) and the BDR (Backup Designated Router). They describe the routers attached to a particular network and are flooded within a single area (area 0 for example).


What is the routing metric OSPF is based on?
Bandwith.
Formula: Cost = 100,000,000 / bandwidth in bits per seconds
The cost of a 100 MBbps connection would be:
1000,000,000 / 100,000,000 =1
Based on the schema above -- if adjacencies are established with only with the DR (Designated Router) and BDR (Backup Designated Router)- what is the circuit count?
Formula:
2(n - 1) where n is the number of routers in the network.
2(5 - 1) = 8 circuits.
A circuit can also be thought of as an adjacency or connection.
Count four going into the DR and 4 going into the BDR for a total of 8.
Note: OSPF avoids synchronizing between every pair of routers in the network by using a DR and BDR. This way adjacencies are formed only to the DR and BDR, and the number of LSAs sent over the network is reduced. Now only the DR and BDR have four adjacencies, and all the other routers have two.
On an OSPF-enabled router -- what is the router ID and where does an OSPF-enabled router receive its router ID?
To initialize - OSPF must be able to define a router ID. The most common and stable source for a router ID is the IP address set on the logical loopback interface that is always available. If no logical interface is defined -- then the router receives its ID from the highest IP address on the physical interfaces.
Note: If two loopback addresses are defined -- it will use the highest loopback address. Think highest logical or highest physical interface address.
Name five OSPF network types:
Broadcast networks: Ethernet/Token Ring. OSPF-enabled routers on broadcast networks elect a DR (Designated Router) and BDR (Backup Designated Router). All the routers in the network form adjacencies with the DR and BDR. Note: OSPF packets are multicast to the DR and BDR.
NBMA (nonbroadcast multiaccess) networks: Frame Relay/X.25/ATM. NBMA networks can connect more than two routers but have no broadcast functionality. These networks elect an DR and BDR. Note: OSPF packets are unicast.
Point-to-point networks: A physical DS1 (T1) for example.
Point-to-point networks connect a pair of routers and always becomes adjacent.
Point-to-multipoint networks: Point-to-multipoint networks are a special configuration of NBMA networks in which networks are treated as a collection of point-to-point links. Point-to-multipoint networks do not elect a DR or BDR. Note: OSPF packets are multicast.

Virtual links: Virtual links area special configuration that the router interprets as unnumbered point-to-point networks. The network administrator creates/defines virtual links.


What is routing?
Routing is the process in which items are forwarded from one location to another. Routing is a hop-by-hop paradigm.
A Cisco router performs routing and switching functions. Describe what each function does.
Routing is a way to learn and maintain awareness of the network topology. Each router maintains a routing table in which it looks up the destination Layer 3 address to get the packet one step closer to its destination.
The switching function is the actual movement of temporary traffic through the router, from an inbound interface to an outbound interface.

What are the three types of routes you can use in a Cisco router?
The three types of routes are static routes, dynamic routes, and default routes.

What is the difference between static and dynamic routes?
Static routes are routes that an administrator manually enters into a router. Dynamic routes are routes that a router learns automatically through a routing protocol.

What is a default route?
Also known as the gateway of last resort, a default route is a special type of static route with an all-zeros network and network mask. The default route is used to route any packets to a network that a router does not directly know about to a next-hop router. By default, if a router receives a packet to a destination network that is not in its routing table, it drops the packet. When a default route is specified, the router does not drop the packet. Instead, it forwards the packet to the IP address specified in the default route.

What is a routing protocol?
A routing protocol defines the set of rules used by a router when it communicates with neighboring routers. Routing protocols listens for packets from other participants in order to learn and maintain a routing table.

What is administrative distance?
Administrative distance (AD) is an integer from 0 to 255 that rates the trustworthiness of routing information received on a router from a neighboring router. The AD is used as the tiebreaker when a router has multiple paths from different routing protocols to the same destination. The path with the lower AD is the one given priority.




What are the three classes of routing protocols?
1) Distance vector 2) Link-state 3) Balanced hybrid
What is the AD for each of the following?
Directly connected interface 0
Static route 1
EIGRP 90
IGRP 100
OSPF 110
RIP 120
External EIGRP 170
Unknown 255
How do distance vector routing protocols function?
Also known as Bellman-Ford-Fulkerson algorithms, distance vector routing protocols pass complete routing tables to neighboring routers. Neighboring routers then combine the received routing table with their own routing table. Each router receives a routing table from its directly connected neighbor. Distance vector routing tables include information about the total cost and the logical address of the first router on the path to each network they know about.

How do distance vector routing protocols keep track of any changes to the internetwork?
Distance vector routing protocols keep track of an internetwork by periodically broadcasting updates out all active interfaces. This broadcast contains the entire routing table. This method is often called routing by rumor.
Slow convergence of distance vector routing protocols can cause inconsistent routing tables and routing loops.

What are some mechanisms that distance vector protocols implement to prevent routing loops and inconsistent routing tables?
Here are some of the ways distance vector routing protocols prevent routing loops and inconsistent routing tables:
• Maximum hop count• Split horizon
• Route poisoning• Holddowns

What is split horizon?
The rule of split horizon is that it is never useful to send information about a route back in the direction from which the original update came.

What is convergence?
Convergence is when all routers have consistent knowledge and correct routing tables.

What is route poisoning?
With route poisoning, when a distance vector routing protocol notices that a route is no longer valid, the route is advertised with an infinite metric, signifying that the route is bad. In RIP, a metric of 16 is used to signify infinity. Route poisoning is used with holddowns.

What are hold-down timers?
Hold-down timers prevent regular update messages from reinstating a route that might have gone bad. Hold-down timers also tell routers to hold for a period of time any changes that might affect routes.

What are triggered updates?
When a router notices that a directly connected subnet has changed state, it immediately sends another routing update out its other interfaces rather than waiting for the routing update timer to expire. Triggered updates are also known as Flash updates.

What is IP RIP?
IP RIP is a true distance vector routing protocol that sends its complete routing table out all active interfaces every 30 seconds. IP RIP uses a hop count as its metric to determine the best path to a remote network. The maximum allowable hop count is 15, meaning that 16 is unreachable. There are two versions of RIP. Version 1 is classful, and version 2 is classless. IP RIP can load-balance over as many as six equal-cost paths.

What four timers does IP RIP use to regulate its performance?
Here are the four timers that IP RIP uses to regulate its performance: • Route update timer Time between router updates. The default is 30 seconds.• Route invalid timer Time that must expire before a route becomes invalid. The default is 180 seconds.• Route hold-down timer If IP RIP receives an update with a hop count higher than the metric recorded in the routing table, the router goes into holddown for 180 seconds.• Route flush timer Time from when a route becomes invalid to when it is removed from the routing table. The default is 240 seconds.

How do you stop RIP updates from propagating out an interface on a router?
Sometimes you do not want RIP updates to propagate across the WAN, wasting valuable bandwidth or giving out valuable information about your internetwork. The easiest way to stop RIP updates from propagating out an interface is to use the passive-interface global configuration command.

How do you display the contents of a Cisco IP routing table?
The show ip route command displays the Cisco routing table's contents.

What is Interior Gateway Routing Protocol (IGRP)?
IGRP is a Cisco proprietary distance vector routing protocol. IGRP has a default hop count of 100 hops, with a maximum hop count of 255. IGRP uses bandwidth and line delay as its default metric, but it can also use reliability, load, and MTU.



How do you enable IGRP on a Cisco router?
The way you enable IGRP on a Cisco router is similar to the way you enable RIP, except you specify IGRP as the protocol and add an autonomous system number. For example:
RouterA(config)#router igrp 10 (10 is the AS number)
RouterA(config-router)#network 192.168.0.0
RouterA(config-router)#network 192.168.1.0
RouterA(config-router)#network 192.168.2.0

What four timers does IGRP use to regulate its performance?
The four timers IGRP uses to regulate its performance are as follows:

• Route update timer Time between router updates The default is 90 seconds.
• Route invalid timer Time that must expire before a route becomes invalid . The default is 270 seconds.
• Route hold-down timer If a destination becomes unreachable, or if the next-hop router increases the metric recording in the routing table, the router goes into holddown for 280 seconds.
• Route flush timer[md]Time from when a route becomes invalid to when it is removed from the routing table. The default is 630 seconds.

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CCNP Based INTERVIEW QUESTIONS Part 6

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FRAME RELAY
What protocol does Frame Relay rely on for error checking?
Frame Relay does not rely on any certain protocol for error checking. Instead, it relies on upper-layer protocols to provide error checking. For example, Frame Relay relies on TCP to provide error checking in an IP network.

At what layers of the OSI model does Frame Relay operate?
Frame Relay operates at the two lower layers of the OSI model (data link and physical).

What is the difference between switched virtual circuits (SVCs) and permanent virtual circuits (PVCs)?
SVCs are virtual circuits that are dynamically established when data needs to be transferred and that are terminated when data transmission is complete. SVCs consist of four states: call setup, data transfer, idle, and call termination. PVCs are permanently established virtual circuits that operate in one of two states: idle or data transfer. When the PVC is idle, the connection between the DTE devices is still active.

What is a Data Link Connection Identifier (DLCI)?
A DLCI is a number that identifies the logical circuit between the router and the Frame Relay switch. It is the Frame Relay Layer 2 address. The Frame Relay switch maps DLCIs between each pair of routers to create a PVC. For IP devices at the end of each virtual circuit to communicate, their IP addresses need to be mapped to DLCIs. If you are running Cisco IOS 11.2 or later, mapping is done automatically using Inverse ARP. DLCIs have local significance. Think of DLCIs as the MAC address of the Frame Relay network.

What is the committed information rate (CIR)?
The CIR is the committed information rate, by the service provider, in bits per second, at which data will be transferred. The service provider sends any data in excess of this rate if its network has capacity at that time.

How does Frame Relay use Inverse ARP?
Frame Relay uses Inverse ARP as a way to dynamically map a network layer address to a DLCI. With Inverse ARP, the router can discover the network address of a device associated with a VC.

What is the Local Management Interface (LMI)?
The LMI is a signaling standard between a CPE device (a router) and the Frame Relay switch that is responsible for managing and maintaining status between the devices. It is autosensed with Cisco IOS Release 11.2 and later.

In Frame Relay, what is Forward Explicit Congestion Notification (FECN)?
The FECN is the bit in the Frame Relay header that signals to anyone receiving the frame (switches and DTEs) that congestion is occurring in the same direction as the frame. Switches and DTEs can react by slowing the rate at which data is sent in that direction.


What is Backward Explicit Congestion Notification (BECN)?
The BECN is the bit in the Frame Relay header that signals to switches and DTEs receiving the frame that congestion is occurring in the direction opposite (backward) that of the frame. If switches and DTE devices detect that the BECN bit in the Frame Relay header is set to 1, they slow the rate at which data is sent in that direction.

In the Frame Relay header, what is the discard eligibility (DE) bit?
If congestion is detected on the Frame Relay network, the DE bit is turned on in the Frame Relay header. The DE bit is turned on for frames that are in excess of the CIR. The DE bit tells a switch which frames to discard if they must be discarded.

What is the default LMI type for Cisco routers that are configured for Frame Relay?
The default LMI for Cisco routers configured for Frame Relay is Cisco. If you are running Cisco IOS Release 11.2 or later, the Cisco router tries to autosense which LMI type the Frame Relay switch is using. If it cannot autosense the LMI type, the router uses Cisco as its LMI type. The three types of LMIs supported by Cisco routers are:
Cisco
ANSI
Q933a

When a router receives LMI information, it updates its VC status to one of three states. What are these three states?
The three states that a VC uses to update its status are as follows:
Active state The connection is active, and routers can exchange data.
Inactive state The local connection to the Frame Relay switch is working, but the remote router's connection to the Frame Relay switch is not working.
Deleted state Indicates that no LMIs are being received from the Frame Relay switch or that there is no service between the router and the Frame Relay switch.

How do you enable Frame Relay on a Cisco router?
To enable Frame Relay on a Cisco router, you must first enable the serial interface for Frame Relay encapsulation with the encapsulation frame-relay interface command:

RouterB(config)#int s 0
RouterB(config-if)#ip address 192.168.1.1 255.255.255.0
RouterB(config-if)#encapsulation frame-relay


The default encapsulation for a serial interface configured for Frame Relay is cisco. If you are connecting to a non-Cisco router, how do you change the encapsulation type?
If you are connecting to a non-Cisco router in a Frame Relay network, you need to specify ietf as the encapsulation type:

RouterB(config-if)#ip address 192.168.1.1 255.255.255.0
RouterB(config-if)#encapsulation frame-relay ietf



If you are using Cisco IOS Release 11.1 or earlier, or if you do not want to autosense the LMI type, how do you define the LMI type on a Cisco router?
To define the LMI type on a Cisco router, use the frame-relay lmi-type {ansi cisco q933a} interface command:

RouterB(config-if)#ip address 192.168.1.1 255.255.255.0
RouterB(config-if)#encapsulation frame-relay
RouterB(config-if)#frame-relay lmi-type ansi

If Inverse ARP is disabled on your router, how do you reenable it?
Inverse ARP is enabled by default on a Cisco router. If it is disabled, reenable it by using the following command:
RouterB(config-if)#frame-relay inverse-arp [protocol] [dlci]
Supported protocols indicated by the protocol option include ip, ipx, decnet, appletalk, vines, and xns.

If a remote router does not support Inverse ARP, you must define the address-to-DLCI table
statically. How do you create these static maps?
To define static maps on a Cisco router, use the following command:
RouterA(config-if)#frame-relay map protocol protocol-address dlci [broadcast] [ietf cisco] [payload-compress packet-by-packet]
where:
• protocol defines the supported protocol bridging or LLC.
• protocol-address is the remote router's network layer address.
• dlci defines the remote router's local DLCI.
• broadcast specifies whether you want to forward broadcasts over the VC, permitting dynamic routing protocols over the VC.• ietf cisco is the encapsulation type.

What Cisco IOS command displays the LMI traffic statistics and LMI type?
The show frame-relay lmi command displays the LMI traffic statistics and LMI type:
RouterA#show frame-relay lmi
LMI Statistics for interface Serial0 (Frame Relay DTE)
LMI TYPE = CISCO Invalid Unnumbered info 0
Invalid Prot Disc 0 Invalid dummy Call Ref 0
Invalid Msg Type 0 Invalid Status Message 0
Invalid Lock Shift 0 Invalid Information ID 0
Invalid Report IE Len 0 Invalid Report Request 0
Invalid Keep IE Len 0 Num Status Enq. Rcvd 1748
Num Status msgs Sent 1748 Num Update Status Sent 0
Num St Enq. Timeouts 0
routera#

How do you display the current Frame Relay map entries and information about these connections on a Cisco router?
To view the current map entries and information about the connections, use the show frame-relay map command:
RouterA#show frame-relay map

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CCNP Based INTERVIEW QUESTIONS Part 5
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ACCESS LISTS
Besides named access lists, what are the two types of IP access lists?
The two types of IP access lists are standard and extended.

What criteria do standard IP access lists use to filter packets?
Standard IP access lists filter packets by the source address. This results in the packet's being permitted or denied for the entire protocol suite based on the source network IP address.

What criteria do extended IP access lists use to filter packets?
Extended IP access lists filter packets by source address, destination address, protocols, and port numbers.

In what two ways can IP access lists be applied to an interface?
Access lists can be applied as inbound or outbound access lists. Inbound access lists process packets as they enter a router's interface and before they are routed. Outbound access lists process packets as they exit a router's interface and after they are routed.

How many access lists can be applied to an interface on a Cisco router?
Only one access list per protocol, per direction, per interface can be applied on a Cisco router. Multiple access lists are permitted per interface, but they must be for a different protocol.

How are access lists processed?
Access lists are processed in sequential, logical order, evaluating packets from the top down, one statement at a time. As soon as a match is made, the permit or deny option is applied, and the packet is not applied to any more access list statements. Because of this, the order of the statements within any access list is significant.

What is at the end of each access list?
At the end of each access list, an implicit deny statement denies any packet not filtered in the access list.

What are the number ranges used to define standard and extended IP access lists?
The number ranges used to define standard and extended IP access lists are as follows:
• Standard IP access lists 1 to 99 and 1300 to 1999• Extended IP access lists 100 to 199 and 2000 to 2699

When implementing access lists, what are wildcard masks?
Wildcard masks define the subset of the 32 bits in the IP address that must be matched. Wildcards are used with access lists to specify a host, network, or part of a network. Wildcard masks work exactly the opposite of subnet masks. In subnet masks, 1 bits are matched to the network portion of the address, and 0s are wildcards that specify the host range. In wildcard masks, when 0s are present, the octet address must match.

What is the IOS command syntax used to create a standard IP access list?
Here is the command syntax to create a standard IP access list:
access-list access-list-number {permit deny} source-address [wildcard mask]access-list-number is a number from 1 to 99.
For example:
RouterA(config)#access-list 10 deny 192.168.0.0 0.0.0.255

How can you display all access lists on a Cisco router?
To display all access lists on a Cisco router, use the show access-list command: RouterA#show access-list Standard IP access list 10 deny 192.168.0.0, wildcard bits 0.0.0.255 Extended IP access list 101 permit tcp any any eq www permit udp any any eq domain permit udp any eq domain any permit icmp any any deny tcp 192.168.10.0 0.0.0.255 any eq www

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CCNP Based INTERVIEW QUESTIONS Part 4

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CABLING TECHNOLOGY
What is a straight-through cable, and when would you use it?
A straight-through cable is the same at both ends. A straight-through cable uses pins 1, 2, 3, and 6. The send and receive wires are not crossed. You should use a straight-through cable when connecting dissimilar devices. Examples include connecting PCs to switches or hubs or a router to a switch or a hub.

What is a crossover cable, and when would you use it?
A crossover cable is a cable that has the send and receive wires crossed at one of the ends. On a Category 5 cable, the 1 and 3 wires and the 2 and 6 wires are switched on one of the cable's ends. You should use a crossover cable when connecting similar devices, such as connecting a router to a router, a switch to a switch or hub, a hub to a hub, or a PC to a PC.
Important tip -- Router (think of it as a PC) to PC via 10BaseT (NIC) uses a "crossover cable". (contradicts the rule)

How do you set up a console session to a Cisco device?
To set up a console session to a Cisco device, you connect a rollover cable to the console port on the Cisco device. You then connect the other end to your PC and configure a terminal emulation application to the following com settings: 9600 bps, 8 data bits, no parity, 1 stop bit, and no flow control.

What is the maximum cable length for each of the following?
The maximum cable lengths are as follows:
10Base2 (thinnet) 185 meters
10Base5 (thicknet) 500 meters
10BaseT 100 meters
10BaseFL 2000 meters (400 meters in a shared environment and 2000 meters in a point-to-point environment)
100BaseT 100 meters

What does Base stand for in 10BaseT and 100BaseT?
Base in 10BaseT and 100BaseT stands for baseband. Baseband is a network technology in which only one carrier frequency (signal) is used.

What is the difference between baseband and broadband?
Baseband is a network technology in which only one carrier frequency is used (such as Ethernet). Broadband is a network technology in which several independent channels are multiplexed into one cable (for example, a T1 line).

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CCNP Based INTERVIEW QUESTIONS Part 3

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INTERNETWORKING
What are the three layers of the Cisco Hierarchical Model?
The three layers of the Cisco Hierarchical Model are: 1
the access layer
The distribution layer
The core layer

In the Cisco Hierarchical Model, what is the function of the access layer?
Sometimes referred to as the desktop layer, the access layer is the point at which users connect to the network through low-end switches. Some functions of the access layer include:
Connectivity into the distribution layer
Shared Bandwidth
MAC Address filtering (switching)
Segmentation

What is the function of the distribution layer in the Cisco Hierarchical Model?
The distribution layer is also known as the workgroup layer. It is the demarcation point between the access and core layers of the network. Its primary function is to provide routing, filtering, and WAN access. The distribution layer determines how packets access the core, so it is the layer at which to implement policy-based connectivity. Some functions include the following:
Collection point for access layer devices
Broadcast and multicast domain segmentation
Security and filtering services such as firewalls and access lists
Providing translation between different media types
Inter-VLAN routing

What is the role of the core layer in the Cisco Hierarchical Model?
The core layer is the backbone of the network. Its main function is to switch traffic as fast as possible. Therefore, it should not perform any filtering to slow down traffic.
The ISO's OSI Reference Model contains seven layers. What are they? Include the layer number and name of each layer in your answer.
The seven layers of the OSI model are as follows:
Layer 7 - Application layer
Layer 6 - Presentation layer
Layer 5 - Session layer
Layer 4 - Transport layer
Layer 3 - Network layer
Layer 2 - Data link layer
Layer 1 - Physical layer

What are some reasons that the industry uses a layered model?
Here are some reasons why the industry uses a layered model:
It encourages industry standardization by defining what functions occur at each level.
It allows vendors to modify or improve components at only one layer versus rewriting the whole protocol stack.
It helps interoperability by defining standards for the operations at each level.
It helps with troubleshooting.


What does the application layer (Layer 7) of the OSI model do, and what are some examples of this layer?
The application layer is the layer that is closest to the user. This means that this layer interacts directly with the software application. The application layer's main function is to identify and establish communication partners, determine resource availability, and synchronize communication. Some examples include the following:
TCP/IP applications such as Telnet, File Transfer Protocol (FTP), Simple Mail Transfer Protocol (SMTP), WWW, and HTTP.
OSI applications such as Virtual Terminal Protocol, File
Transfer, Access, and Management (FTAM), and Common Management Information Protocol (CMIP).

In the OSI model, what are the responsibilities of the presentation layer (Layer 6)? Give some examples of this layer.
Also known as the translator, the presentation layer provides coding and conversion functions to application layer data. This guarantees that the application layer on another system can read data transferred from the application layer of a different system. Some examples of the presentation layer are:
Compression, decompression, and encryption
JPEG, TIFF, GIFF, PICT, QuickTime, MPEG, and ASCII

What are the functions of the session layer (Layer 5)? Give some examples.
The session layer is responsible for creating, managing, and ending communication sessions between presentation layer entities. These sessions consist of service requests and responses that develop between applications located on different network devices. Some examples include SQL, RPC, NFS, X Window System, ZIP, NetBIOS names, and AppleTalk ASP.

What is the transport layer (Layer 4) responsible for? Give some examples of transport layer implementations.
The transport layer segments and reassembles data from upper-layer applications into data streams. It provides reliable data transmission to upper layers. End-to-end communications, flow control, multiplexing, error detection and correction, and virtual circuit management are typical transport layer functions. Some examples include TCP, UDP*, and SPX.
Note: watch out for end-to-end on communications on the exam! Transport layer.

* Error correction does not apply to UDP - connection-less - unreliable.....


What is flow control, and what are the three methods of implementing it?
Flow control is the method of controlling the rate at which a computer sends data, thus preventing network congestion. The three methods of implementing flow control are
Buffering
Congestion avoidance
Windowing
Almost certain to be on the exam.


Describe the function of the network layer (Layer 3), and give some examples of network layer implementations.
The network layer provides internetwork routing and logical network addresses. It defines how to transport traffic between devices that are not locally attached. The network layer also supports connection-oriented and connectionless service from higher-layer protocols. Routers operate at the network layer. IP, IPX, AppleTalk, and DDP are examples of network layer implementations.

Are network layer addresses physical or logical?
Network layer addresses are logical addresses specific to the network layer protocol being run on the network. Each network layer protocol has a different addressing scheme. They are usually hierarchical and define networks first and then host or devices on that network. An example of a network address is an IP address, which is a 32-bit address often expressed in decimal format. 192.168.0.1 is an example of an IP address in decimal format.
How do routers function at the network layer of the OSI model?
Routers learn, record, and maintain awareness of different networks. They decide the best path to these networks and maintain this information in a routing table. The routing table includes the following:
Network addresses, which are protocol-specific. If you are running more than one protocol, you have a network address for each protocol.
The interface the router uses to route a packet to a different network.
A metric, which is the distance to a remote network or the weight of the bandwidth, load, delay, and reliability of the path to the remote network.
Routers create broadcast domains. One interface on a router creates a single broadcast domain and collision domain. However, an interface on a switch creates only a single collision domain.
In addition to learning the remote network and providing a path to the network, what other functions do routers carry out?
Routers perform these tasks:
Routers, by default, do not forward broadcasts or multicasts.
Routers can perform bridging and routing functions.
If a router has multiple paths to a destination, it can determine the best path to the destination.
Routers forward traffic based on Layer 3 destination addresses.
Routers can connect Virtual LANs (VLANs).
Routers can provide quality of service for specified types of network traffic.
What is the responsibility of the data link layer (Layer 2)?
The data link layer provides functional and procedural means for connectionless mode among network entities, and for connection mode entities it provides the establishment, maintenance, and release of data link connections among network entities and for the transfer of data link service data units. The data link layer translates messages from the network layer into bits for the physical layer, and it enables the network layer to control the interconnection of data circuits within the physical layer. Its specifications define different network and protocol characteristics, including physical addressing, error notification, network topology, and sequencing of frames. Data link protocols provide the delivery across individual links and are concerned with the different media types, such as 802.2 and 802.3. The data link layer is responsible for putting 1s and 0s into a logical group. These 1s and 0s are then put on the physical wire. Some examples of data link layer implementations are IEEE 802.2/802.3, IEEE 802.5/802.2, packet trailer (for Ethernet, the FCS or CRC), FFDI, HDLC, and Frame Relay.

The IEEE defines what two sublayers of the data link layer?
The two sublayers of the data link layer are
The Logical Link Control (LLC) sublayer
The Media Access Control (MAC) sublayer
These two sublayers provide physical media independence.

For what is the LLC sublayer responsible?
The Logical Link Control (802.2) sublayer is responsible for identifying different network layer protocols and then encapsulating them to be transferred across the network. An LLC header tells the data link layer what to do with a packet after it is received.

What functions does the Media Access Control (MAC) sublayer provide?
The MAC sublayer specifies how data is placed and transported over the physical wire. The LLC layer communicates with the network layer, but the MAC layer communicates downward directly to the physical layer. Physical addressing (MAC addresses), network topologies, error notification, and delivery of frames are defined at this sublayer.

What are some network devices that operate at the data link layer?
Bridges and switches are network devices that operate at the data link layer. Both devices filter traffic by MAC addresses.

What is the function of the OSI model's physical layer (Layer 1)? Give some examples of physical layer implementations.
The physical layer defines the physical medium. It defines the media type, the connector type, and the signaling type (baseband versus broadband). This includes voltage levels, physical data rates, and maximum cable lengths. The physical layer is responsible for converting frames into electronic bits of data, which are then sent or received across the physical medium. Twisted pair, coaxial cable, and fiber-optic cable operate at this level. Other implementations at this layer are repeaters/hubs, RJ-45.

The Ethernet and IEEE 802.3 standards define what three physical wiring standards that operate at 10 Mbps?
These physical wiring standards operate at 10 Mbps:
10Base2
10Base5
10BaseT
What are collision domains?
In Ethernet segments, devices connect to the same physical medium. Because of this, all devices receive all signals sent across the wire. If two devices send a packet at the same time, a collision occurs. In the event of a collision, the two devices run a backoff algorithm and resend the packet. The devices retransmit up to 15 times. The first station to detect a collision issues a jam signal. When a jam signal is sent from a workstation, it affects all of the machines on the segment, not just the two that collided; when the jam signal is on the wire, no workstations can transmit data. The more collisions that occur in a network, the slower it will be, because the devices will have to resend the packet. A collision domain defines a group of devices connected to the same physical medium.

What are broadcast domains?
A broadcast domain defines a group of devices that receive each others' broadcast messages. As with collisions, the more broadcasts that occur on the network, the slower your network will be. This is because every device that receives a broadcast must process it to see if the broadcast is intended for it.

What devices are used to break up collision and broadcast domains?
Switches and bridges are used to break up collision domains. They create more collision domains and fewer collisions. Routers are used to break up broadcast domains. They create more broadcast domains and smaller broadcast areas.

How do the different layers of the OSI model communicate with each other?
Each layer of the OSI model can communicate only with the layer above it, below it, and parallel to it (a peer layer). For example, the presentation layer can communicate with only the application layer, session layer, and presentation layer on the machine it is communicating with. These layers communicate with each other using protocol data units (PDUs). These PDUs control information that is added to the user data at each layer of the model. This information resides in fields called headers (the front of the data field) and trailers (the end of the data field).
What is data encapsulation?
A PDU can include different information as it goes up or down the OSI model. It is given a different name according to the information it is carrying (the layer it is at). When the transport layer receives upper layer data, it adds a TCP header to the data; this is called a segment. The segment is then passed to the network layer, and an IP header is added; thus, the data becomes a packet. The packet is passed to the data link layer, thus becoming a frame. This frame is then converted into bits and is passed across the network medium. This is data encapsulationApplication layer -- Data
Transport layer -- Segment
Network layer -- Packet
Data link layer -- Frame
There is also the Physical Layer -- Bits

What is the difference between a routing protocol and a routed protocol?
Routing protocols determine how to route traffic to the best location of a routed protocol. Examples of routing protocols are RIP, EIGRP, OSFP, and BGP. Examples of routed protocols are IP and IPX.

What 3 devices are used to segment a LAN?
Router
Switch
Bridge

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CCNP Based INTERVIEW QUESTIONS Part 2

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WAN

The three WAN connection types available are leased lines, circuit-switched, and packet-switched. Define the differences between each connection type.

Leased lines are dedicated point-to-point lines that provide a single preestablished WAN communication path from the customer's network to the remote network. Leased lines are usually employed over synchronous connections. They are generally expensive and are always up.
Circuit-switched connections are dedicated for only the duration of the call. The telephone system and ISDN are examples of circuit-switched networks. Packet-switched connections use virtual circuits (VCs) to provide end-to-end connectivity.
Packet-switched connections are similar to leased lines, except that the line is shared by other customers. A packet knows how to reach its destination by programming of switches. Frame Relay is an example of a packet-switched connection.

Define customer premises equipment (CPE), and give an example.
CPE is equipment that is located on the customer's (or subscriber's) premises. It is equipment owned by the customer or equipment leased by the service provider to the customer. An example is your router.

What is the demarcation point (demarc)?
The demarc is the point where the CPE ends and the local loop begins. It is the last responsibility of the service provider and is usually an RJ-45 jack located close to the CPE. Think of the demarc as the boundary between the customer's wiring and the service provider's wiring.
What is the local loop?
The local loop is the physical cable that extends from the demarc to the central office.

Describe the central office (CO).
The CO is the telco switching facility that connects the customer to the provider's switching network. The CO is sometimes referred to as a point of presence. It is the point where the local loop gains access to the service provider's access lines.

What is the toll network?
All the telco switches, COs, and trunk lines inside the WAN provider's network are the toll network.

What are synchronous links?
Synchronous links have identical frequencies and contain individual characters encapsulated in control bits, called start/stop bits, that designate the beginning and end of each character. Synchronous links try to use the same speed as the other end of a serial link.

What are Asynchronous links?
Asynchronous links send digital signals without timing. Asynchronous links agree on the same speed, but there is no check or adjustment of the rates if they are slightly different. Only 1 byte per transfer is sent.



List some typical Layer 2 encapsulation methods for WAN links.
. High-Level Data Link Control (HDLC)
• Point-to-Point Protocol (PPP)
• Serial Line Internet Protocol (SLIP)
• X.25/Link Access Procedure, Balanced (LAPB)
• Frame Relay• Asynchronous Transfer Mode (ATM)

Describe HDLC.
HDLC was derived from Synchronous Data Link Control (SDLC). It is the default encapsulation type on point-to-point dedicated links and circuit-switched connections between Cisco routers. It is an ISO-standard bit-oriented data-link protocol that encapsulates data on synchronous links. HDLC is a connection-oriented protocol that has very little overhead. HDLC lacks a protocol field and therefore cannot encapsulate multiple network layer protocols across the same link. Because of this, each vendor has its own method of identifying the network-layer protocol. Cisco offers a propriety version of HDLC that uses a type field that acts as a protocol field, making it possible for multiple network-layer protocols to share the same link.

By default, Cisco uses HDLC as its default encapsulation method across synchronous lines (point-to-point links). If a serial line uses a different encapsulation protocol, how do you change it back to HDLC?
To change a serial line back to HDLC, use the following interface command on the serial interface you want to change: Router(config-if)#encapsulation hdlc

What is the Point-to-Point Protocol (PPP)?
PPP is an industry-standard protocol that provides router-to-router or router-to-host connections over synchronous and asynchronous links. It can be used to connect to other vendors' equipment. It works with several network-layer protocols, such as IP and IPX. PPP provides authentication through PAP or CHAP.

Describe X.25/LAPB.
X.25/LAPB is an ITU-T standard that has a tremendous amount of overhead because of its strict timeout and windowing techniques. LAPB is the connection-oriented protocol used with X.25. It uses the ABM (Asynchronous Balance Mode) transfer mode. X.25/LAPB was used in the 1980s when WAN links were not as error-free as they are today. X.25 is a predecessor of Frame Relay. X.25 supports both switched and permanent virtual circuits.

What is Frame Relay?
An industry standard, Frame Relay is a switched data link layer protocol that uses virtual circuits to identify the traffic that belongs to certain routers. It provides dynamic bandwidth allocation and congestion control.

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CCNP Based INTERVIEW QUESTIONS Part 1

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LAN
What is carrier sense multiple access collision detect (CSMA/CD)?
CSMA/CD describes the Ethernet access method. In CSMA/CD, many stations can transmit on the same cable, and no station has priority over any other. Before a station transmits, it listens on the wire to make sure no other station is transmitting. If no other station is transmitting, the station transmits across the wire. CSMA/CD is all about devices taking turns using the wire.

What are MAC addresses?
For computers to identify each other on the data link layer, they need a MAC address (hardware address). All devices on a LAN must have a unique MAC address. A MAC address is a 48-bit (six octet) address burned into a network interface card. The first three octets (24 bits) of the MAC address indicate the vendor that manufactured the card. This is called the Organization Unique Identifier (OUI). The last three octets of the MAC address are the unique host address. An example of a MAC address is 00-80-C6-E7-9C-EF.

What are the three types of LAN traffic?
The three types of LAN traffic are:
Unicasts
Broadcasts
Multicasts

What are unicast frames?
Unicast frames are the most common type of LAN traffic. A unicast frame is a frame intended for only one host. In unicast frames, the only station that processes the frame is the station that has its own MAC address in the destination portion of the packet.

What are broadcast frames?
Broadcast frames are frames intended for everyone. Stations view broadcast frames as public service announcements. All stations receive and process broadcast frames. In large networks, broadcasts can bring the network to a crawl, because every computer must process them.

What is the destination address of broadcast frames?
The destination address of broadcast frames (Layer 2 broadcast addresses) is FF-FF-FF-FF-FF-FF, or all 1s in binary.

What are multicast frames?
Multicast frames address a group of devices that have a common interest. These frames allow the source to send only one copy of the frame on the network even though it is intended for several stations. Only stations that have a card that is configured to receive multicast frames process them. All other stations discard multicast frames.


What devices can you use to segment a LAN at Layer 1, Layer 2, and Layer 3?
Three devices you can use to segment a LAN are:
Hubs/repeaters (Layer 1)
Bridges/switches (Layer 2) - physical addresses
Routers (Layer 3) - logical addresses

What happens when you segment the network with hubs/repeaters?
Because hubs and repeaters operate at the physical layer of the OSI model, segmenting a network with these devices appears as an extension to the physical cable. Hubs and repeaters are transparent to devices. They are unintelligent devices. All devices that connect to a hub/repeater share the same bandwidth. Hubs/repeaters create a single broadcast and collision domain.

What is the advantage of segmenting a network with bridges/switches?
Bridges/switches operate at Layer 2 of the OSI model and filter by MAC address. Each port on a bridge/switch provides full-dedicated bandwidth and creates a single collision domain. Because bridges/switches operate at Layer 2 of the OSI model, they cannot filter broadcasts, and they create a single broadcast domain. For the CCNA test, remember that switches create more collision domains and fewer collisions.

What is the difference between bridges and switches?
Bridges and switches function the same way; the only difference is in how they are implemented. Bridges are implemented by software and usually have a couple of network ports. Switches are implemented in hardware by ASIC chips and have many ports.

What are the advantages and disadvantages of segmenting the LAN with routers?
An advantage of segmenting the LAN with routers is that each interface on a router creates a single broadcast and collision domain. Routers operate at Layer 3 of the OSI model and do not propagate broadcasts. Some disadvantages are that routers are not transparent and are implemented in software, thus introducing latency in the network.

What is the Maximum Transmission Unit (MTU) for an Ethernet frame?
1500 bytes is the MTU for an Ethernet frame. You will notice that some publications state that the MTU for Ethernet is 1518 bytes. This is correct also. But what is the true answer? The MTU for Ethernet, including the header, source and destination address, data, and CRC is 1518 bytes. The MTU for the data portion of the frame is 1500 bytes.

What three major functions do Layer 2 switches provide?
The three major functions that Layer 2 switches provide are
Address learning
Packet forwarding/filtering
Loop avoidance by spanning tree
What are some advantages of switches?
Some advantages of switches are as follows:
They increase available network bandwidth.
They reduce the number of users per segment.
They provide dedicated bandwidth to each segment.
Transparent bridging (switching) provides five bridging functions to determine what to do when it receives a frame.

What are these five processes?
The five processes are:
Learning
Flooding
Filtering
Forwarding
Aging

In transparent bridging, what is the learning process?
The first process a bridge goes through when it is powered on is the learning process. The MAC address table on the bridge contains no entries, and the bridge goes through the learning process to record all workstations on every interface. In the learning process, the bridge records the source MAC address and source port number in the MAC address table every time it sees a frame.

In transparent bridging, what is the flooding process?
When a bridge is first turned on, it has no MAC address in its table. When a switch receives a unicast frame, it knows the source address and port from which the unicast frame came, but no entry exists in its table for the destination address. This is called an unknown unicast frame. When a switch receives an unknown unicast frame, it sends the frame out all forwarding interfaces on the bridge except the interface that received the frame. This process is the flooding process.

In transparent bridging, what is the filtering process?
The filtering process occurs when the source and destination addresses reside on the same interface on the bridge. Because the bridge does not need to forward a frame in which the destination and source addresses reside on the same interface, it filters the frame and discards it.

In transparent bridging, what is the forwarding process?
The forwarding process occurs when a switch receives a unicast frame and has an entry of the destination address in its MAC table. The switch then forwards the frame to the interface where that destination address resides.

In transparent bridging, what occurs during the aging process?
Every time a bridge learns a source address, it time-stamps the entry. When the bridge sees a frame from this source, it updates the time stamp. If the bridge does not hear from the source for a specific amount of time (called the aging timer), the bridge deletes the entry from its MAC address table. This process is the aging process.
What is the default aging time in transparent bridges?
The default aging timer is 5 minutes.

What is the Spanning-Tree Protocol (STP)?
STP is a loop-prevention bridge-to-bridge protocol. Its main purpose is to dynamically maintain a loop-free network. It does this by sending out Bridge Protocol Data Units (BPDUs), discovering any loops in the topology, and blocking one or more redundant links.

How does STP maintain a loop-free network?
STP maintains a loop-free network by
Electing a root bridge
Electing a root port on each nonroot bridge
Electing designated ports
Putting in the blocking state any port that is not a root port or designated port

In spanning tree, what is a Bridge ID (BID)?
A BID is an 8-byte field that is composed of the bridge's 6-byte MAC address and a 2-byte bridge priority.

What is the default bridge priority in a Bridge ID for all Cisco switches?
32,768

In spanning tree, what is path cost?
Path cost is a calculation to determine the link's bandwidth. It is a value assigned to each port that is based on the port's speed.

What is the spanning tree path cost for each of the following?
10 Mbps
100 Mbps
1 Gbps
The path costs are as follows:
10 Mbps - 100
100 Mbps - 19
1 Gbps - 4

When calculating a loop-free environment, what four-step decision sequence does spanning tree use to determine what will be the root bridge and which ports will forward or block?
The four-step decision sequence that spanning tree uses to determine the root bridge and which port will forward is as follows:
Step 1. The lowest root BID
Step 2. The lowest path cost to the root bridge
Step 3. The lowest sender BID
Step 4. The lowest port ID

How do bridges pass spanning tree information between themselves?
Bridges pass STP information using special frame called Bridge Protocol Data Units (BPDUs).

How often do bridges send BPDUs out active ports?
The default time that bridges send BPDUs out active ports is 2 seconds.
Note: All ports on a switch listen for BPDUs in case there is a topology change.

In STP, how is a root bridge elected?
In STP, the bridge with the lowest BID is elected the root bridge. All ports on the root bridge are placed in the forwarding state and are called designated ports.
Note: The BID is a 6-byte field that is composed of a default priority (32,768) and a MAC address. Because all Cisco switches use the default priority, the switch with the lowest MAC address is elected the root bridge. As a rule of thumb, lower will always win in spanning tree.
After bridges elect the root bridge, what do they do next?
After electing the root bridge, switches elect root ports. A root port is the port on nonroot bridges that is closest to the root bridge. Every nonroot bridge must select one root port.

How do nonroot bridges decide which port they will elect as a root port?
Nonroot bridges use root path cost to determine which port will be the root port. Root path cost is the cumulative cost of all links to the root bridge. The port with the lowest root path cost is elected the bridge's root port and is placed in the forwarding state.

What is the difference between path cost and root path cost?
Path cost is the value assigned to each port. It is added to BPDUs received on that port to calculate the root path cost. Root path cost is defined as the cumulative cost to the root bridge. In a BPDU, this is the value transmitted in the cost field. In a bridge, this value is calculated by adding the receiving port's path cost to the value contained in the BPDU.

If a nonroot bridge has two redundant ports with the same root path cost, how does the bridge choose which port will be the root port?
If a nonroot bridge has redundant ports with the same root path cost, the deciding factor is the port with the lowest port ID (port number).

After the root bridge and root ports are selected, the last step in spanning tree is to elect designated ports. How do bridges elect designated ports?
In spanning tree, each segment in a bridged network has one designated port. This port is a single port that both sends and receives traffic to and from that segment and the root bridge. All other ports are placed in a blocking state. This ensures that only one port on any segment can send and receive traffic to and from the root bridge, ensuring a loop-free topology. The bridge containing the designated port for a segment is called the designated bridge for that segment. Designated ports are chosen based on cumulative root path cost to the root bridge.
Note: Every active port on the root bridge becomes a designated port.

If a bridge is faced with a tie in electing designated ports, how does it decide which port will be the designated port?
In the event of a tie, STP uses the four-step decision process discussed in Question 30. It first looks for the BPDU with the lowest BID; this is always the root bridge. If the switch is not the root bridge, it moves to the next step: the BPDU with the lowest path cost to the root bridge. If both paths are equal, STP looks for the BPDU with the lowest sender BID. If these are equal, STP uses the link with the lowest port ID as the final tiebreaker.

What are the four spanning tree port states?
The four spanning tree port states are
Blocking
Listening
Learning
Forwarding
Remember that root and designated ports forward traffic and that nondesignated ports block traffic but still listen for BPDUs.
Important note: There is another port state - Disabled - (No frames forwarded, no BPDUs heard). If it shows up in the answer options - select it along with the others.

What is the STP blocking state?
When a switch starts, all ports are in the blocking state. This is to prevent any loops in the network. If there is a better path to the root bridge, the port remains in the blocked state. Ports in the blocked state cannot send or receive traffic, but they can receive BPDUs.

What is the STP listening state?
Ports transition from a blocked state to a listening state. In this state, no user data is passed. The port only listens for BPDUs. After listening for 15 seconds (if the bridge does not find a better path), the port moves to the next state, the learning state.

What is the STP learning state?
In the STP learning state, no user data is being passed. The port quietly builds its bridging table. The default time in the learning state is 15 seconds.

What is the STP forwarding state?
After the default time in the learning state is up, the port moves to the forwarding state. In the forwarding state, the port sends and receives data.

What is STP forward delay?
The forward delay is the time it takes for a port to move from the listening state to the learning state or from the learning state to the forwarding state. The default time is 30 seconds.

What is the hello time in STP timers?
The hello time is the time interval between the sending of BPDUs. The default time is 2 seconds.

What is the Max Age timer?
The Max Age timer is how long a bridge stores a BPDU before discarding it. The default time is 20 seconds (ten missed hello intervals).

What is the default time a port takes to transition from the blocking state to the forwarding state?
The default time a port takes to transition from the blocking state to the forwarding state is 50 seconds: 20 seconds for Max Age, 15 seconds for listening, and 15 seconds for learning.

What does STP do when it detects a topology change in the network due to a bridge or link failure?
If spanning tree detects a change in the network due to a bridge or link failure, at least one bridge interface changes from the blocking state to the forwarding state, or vice versa.

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System Administrator Interview Questions Part 2

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1. What’s the difference between local, global and universal groups? Domain local groups assign access permissions to global domain groups for local domain resources. Global groups provide access to resources in other trusted domains. Universal groups grant access to resources in all trusted domains.

2. I am trying to create a new universal user group. Why can’t I? Universal groups are allowed only in native-mode Windows Server 2003 environments. Native mode requires that all domain controllers be promoted to Windows Server 2003 Active Directory.

3. What is LSDOU? It’s group policy inheritance model, where the policies are applied to Local machines, Sites, Domains and Organizational Units.

4. Why doesn’t LSDOU work under Windows NT? If the NTConfig.pol file exist, it has the highest priority among the numerous policies.

5. Where are group policies stored? %SystemRoot%System32\GroupPolicy

6. What is GPT and GPC? Group policy template and group policy container.

7. Where is GPT stored? %SystemRoot%\SYSVOL\sysvol\domainname\Policies\GUID

8. You change the group policies, and now the computer and user settings are in conflict. Which one has the highest priority? The computer settings take priority.

9. You want to set up remote installation procedure, but do not want the user to gain access over it. What do you do? gponame–> User Configuration–> Windows Settings–> Remote Installation Services–> Choice Options is your friend.

10. What’s contained in administrative template conf.adm? Microsoft NetMeeting policies

11. How can you restrict running certain applications on a machine? Via group policy, security settings for the group, then Software Restriction Policies.

12. You need to automatically install an app, but MSI file is not available. What do you do? A .zap text file can be used to add applications using the Software Installer, rather than the Windows Installer.

13. What’s the difference between Software Installer and Windows Installer? The former has fewer privileges and will probably require user intervention. Plus, it uses .zap files.

14. What can be restricted on Windows Server 2003 that wasn’t there in previous products? Group Policy in Windows Server 2003 determines a users right to modify network and dial-up TCP/IP properties. Users may be selectively restricted from modifying their IP address and other network configuration parameters.

15. How frequently is the client policy refreshed? 90 minutes give or take.

16. Where is secedit? It’s now gpupdate.

17. You want to create a new group policy but do not wish to inherit. Make sure you check Block inheritance among the options when creating the policy.

18. What is "tattooing" the Registry? The user can view and modify user preferences that are not stored in maintained portions of the Registry. If the group policy is removed or changed, the user preference will persist in the Registry.

19. How do you fight tattooing in NT/2000 installations? You can’t.

20. How do you fight tattooing in 2003 installations? User Configuration - Administrative Templates - System - Group Policy - enable - Enforce Show Policies Only.

21. What does IntelliMirror do? It helps to reconcile desktop settings, applications, and stored files for users, particularly those who move between workstations or those who must periodically work offline.

22. What’s the major difference between FAT and NTFS on a local machine? FAT and FAT32 provide no security over locally logged-on users. Only native NTFS provides extensive permission control on both remote and local files.

23. How do FAT and NTFS differ in approach to user shares? They don’t, both have support for sharing.

24. Explan the List Folder Contents permission on the folder in NTFS. Same as Read & Execute, but not inherited by files within a folder. However, newly created subfolders will inherit this permission.

25. I have a file to which the user has access, but he has no folder permission to read it. Can he access it? It is possible for a user to navigate to a file for which he does not have folder permission. This involves simply knowing the path of the file object. Even if the user can’t drill down the file/folder tree using My Computer, he can still gain access to the file using the Universal Naming Convention (UNC). The best way to start would be to type the full path of a file into Run… window.

26. For a user in several groups, are Allow permissions restrictive or permissive? Permissive, if at least one group has Allow permission for the file/folder, user will have the same permission.
27. For a user in several groups, are Deny permissions restrictive or permissive? Restrictive, if at least one group has Deny permission for the file/folder, user will be denied access, regardless of other group permissions.

28. What hidden shares exist on Windows Server 2003 installation? Admin$, Drive$, IPC$, NETLOGON, print$ and SYSVOL.

29. What’s the difference between standalone and fault-tolerant DFS (Distributed File System) installations? The standalone server stores the Dfs directory tree structure or topology locally. Thus, if a shared folder is inaccessible or if the Dfs root server is down, users are left with no link to the shared resources. A fault-tolerant root node stores the Dfs topology in the Active Directory, which is replicated to other domain controllers. Thus, redundant root nodes may include multiple connections to the same data residing in different shared folders.

30. We’re using the DFS fault-tolerant installation, but cannot access it from a Win98 box. Use the UNC path, not client, only 2000 and 2003 clients can access Server 2003 fault-tolerant shares.

31. Where exactly do fault-tolerant DFS shares store information in Active Directory? In Partition Knowledge Table, which is then replicated to other domain controllers.

32. Can you use Start->Search with DFS shares? Yes.

33. What problems can you have with DFS installed? Two users opening the redundant copies of the file at the same time, with no file-locking involved in DFS, changing the contents and then saving. Only one file will be propagated through DFS.

34. I run Microsoft Cluster Server and cannot install fault-tolerant DFS. Yeah, you can’t. Install a standalone one.

35. Is Kerberos encryption symmetric or asymmetric? Symmetric.

36. How does Windows 2003 Server try to prevent a middle-man attack on encrypted line? Time stamp is attached to the initial client request, encrypted with the shared key.

37. What hashing algorithms are used in Windows 2003 Server? RSA Data Security’s Message Digest 5 (MD5), produces a 128-bit hash, and the Secure Hash Algorithm 1 (SHA-1), produces a 160-bit hash.

38. What third-party certificate exchange protocols are used by Windows 2003 Server? Windows Server 2003 uses the industry standard PKCS-10 certificate request and PKCS-7 certificate response to exchange CA certificates with third-party certificate authorities.

39. What’s the number of permitted unsuccessful logons on Administrator account? Unlimited. Remember, though, that it’s the Administrator account, not any account that’s part of the Administrators group.

40. If hashing is one-way function and Windows Server uses hashing for storing passwords, how is it possible to attack the password lists, specifically the ones using NTLMv1? A cracker would launch a dictionary attack by hashing every imaginable term used for password and then compare the hashes.

41. What’s the difference between guest accounts in Server 2003 and other editions? More restrictive in Windows Server 2003.

42. How many passwords by default are remembered when you check "Enforce Password History Remembered"? User’s last 6 passwords.

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System Administrator Interview Questions Part 1

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Q : What are SOA records?
Ans : SOA is a Start of Authority record, which is a first record in DNS, which controls the startup behavior of DNS. We can configure TTL, refresh, and retry intervals in this record.

Q : Brief about Disk Management?
Ans : Windows2000 includes a powerful tool to manage disk-it’s called a disk management. Disk management tool is graphical tool. you can use disk management to:
• Create and format partitions
• Upgrade a disk from basic to dynamic
• Revert form a dynamic to basic
• Create and format Simple, Spanned, Striped, Mirrored and Raid-5 volumes and as well as deleted the same.
• Recover from single hard disk failure in Mirrored and Raid-5 volumes.

Simple Volumes
A simple volume is volume that consists of formatted disk space on a sigle hard disk. You can create simple volumes only on dynamic disks. There is no fault tolerance. If it is fails all data in the simple volume is lost unless the data backed up.

Spanned volumes
A spanned volume consists of formatted disk space on more than one hard disk. That is treated as single volume. The primary purpose and use of spanned volumes is to access disk space on more than one hard disk by using a single drive letter. A spanned volume is some times used when a volume becomes full and u wants to enlarge its capacity. Spanned volumes do not perform any fault tolerance function.

Stripped volumes – Raid level 0
A stripped volume consists of identical-sized areas of formatted disk space located on two or more dynamic disks. In a stripped volume data stored,
A block at time, evenly and sequentially, among all of the disks in the stripped volume. Stripped volumes do not perform any fault tolerance function. Stripped volumes provide faster disk access, because the stripped volume store a single file across multiple disks

Mirrored Volumes – Raid level 1
A mirrored volume consists of a simple volume that is exactly duplicated, in its entirety on to a second dynamic disk. A mirrored volume is accessed by using single drive letter. A mirrored volume provides a highest fault tolerance available in win2000.

Raid-5 Volumes
A Raid-5 Volumes consists of identical sized areas of formatted disk space located on three or more dynamic disks. In Raid-5 volume data is stored a block at a time, evenly and sequentially among all of the disks in the volume. Raid-5 volumes to provide fault tolerance. If Raid-5 volume fails the information on the other disk in the volume is used to regenerate the data from the failed disk. If more than one disk in Raid-5 volumes fails, you cannot recover your unless the data is backed up.


Q: Difference b/w NT and 2000?

A: NT SAM database is a flat database. Where as in windows 2000 active directory database is a hierarchical database.

In windows NT only PDC is having writable copy of SAM database but the BDC is only contained read only database. In case of Windows 2000 both DC and ADC is having write copy of the database

Windows NT will not support FAT32 file system. Windows 2000 supports FAT32.
Default authentication protocol in NT is NTLM (NT LAN manager). In windows 2000 default authentication protocol is Kerberos V5. Windows 2000 depends and Integrated with DNS. NT user NetBIOS names Active Directory can be backed up easily with System state data.

Q : What is the process of user authentication (Kerberos V5) in windows 2000.

A : After giving logon credentials an encryption key will be generated which is used to encrypt the time stamp of the client machine. User name and encrypted timestamp information will be provided to domain controller for authentication. Then Domain controller based on the password information stored in AD for that user it decrypts the encrypted time stamp information. If produces time stamp matches to its time stamp. It will provide logon session key and Ticket granting ticket to client in an encryption format. Again client decrypts and if produced time stamp information is matching then it will use logon session key to logon to the domain. Ticket granting ticket will be used to generate service granting ticket when accessing network resources.

Q : WINS AND DNS.
A. DNS is a Domain Naming System, which resolves Host names to IP addresses. It uses fully qualified domain names. DNS is an Internet standard used to resolve host names WINS is a Windows Internet Name Service, which resolves NetBIOS names to IP Address. This is proprietary for Windows.

Q : What is DNS? What are the zones? What are the role? What are the records?

A: DNS standard for Domain Name System. The primary purpose of DNS, which consists of a set of specified naming rules and implementations standards, is to provide host name resolutions.
Zones:
A Zone is storage database for either a dns domain or for a dns domain and one are more of it’s subdomains. This storage database is often implemented as a text file called a zone file.
Zone are not created by default when the DNS server services is installed – they are created and configured by administrator.
Forward lookup zone:
This type zone contain host name to ip address mappings and information about available services for either a DNS domain or DNS domain and one or more sub domains.
Reverse lookup zones:
This type of zones contains IP address to host name mappings.
Standard Primary Zone: This type of zone can be either a forward lookup and reverse lookup zones. In either case, the standard primary zone is master copy of that zone. All other copies of the standard primary zone are standard secondary zones.
Active Directory-integrated zone: This type of zone can be either a forward lookup or reverse lookup zone. In either case the active directory – integrated zone is the master copy of that zone.
Standard Secondary Zone: This type of zone is a copy of either a Standard primary zone or an Active directory-integrated zone. Standard secondary zones must be created on different DNS servers than the DNS server that contains the master copy of the zone. The purpose of standard secondary zones is to provide load balancing and fault tolerance for the zone.

Roles
Standard primary
Standard secondary
Active Directory integrated
Master
Caching
Forwarder
Root Server
SRV Records
Msdcs
Sites
Tcp
Udp

Q : what is the process of DHCP for getting the IP address to the client
A: There is a four way negotiation process b/w client and server
DHCP Discover (Initiated by client)
DHCP Offer (Initiated by server)
DHCP Select (Initiated by client)
DHCP Acknowledgement (Initiated by Server)
DHCP Negative Acknowledgement (Initiated by server if any issues after DHCP offer)

Q: What are the different backup strategies are available ?
A: Normal Backup
Incremental Backup
Differential Backup
Daily Backup
Copy Backup

A) In Differential backup, after taking the backup it will not clear the archive bit, whereas in incremental backup after taking the backup it clears the archive bit.Diffarential backup will take time during the backup, whereas it will take less time during the restore. Incremental backup will take less time during the backup, whereas it will take more time during the restore.

Scenario: I took Full backup on Sunday,incremaental backups from Monday to wednesday. Thursday my server went down.What do i need to do? You need to restore Sunday full backup first and then Monday incremental, like that sequentially till Wednesday.

Q: What is a global catalog
Global catalog is a role, which maintains Indexes about objects. It contains full information of the objects in its own domain and partial information of the objects in other domains. Universal Group membership information will be stored in global catalog servers and replicate to all GC’s in the forest.


Q: What is Active Directory and what is the use of it
Active directory is a directory service, which maintains the relation ship between resources and enabling them to work together. Because of AD hierarchal structure windows 2000 is more scalable, reliable. Active directory is derived from X.500 standards where information is stored is hierarchal tree like structure. Active directory depends on two Internet standards one is DNS and other is LDAP. Information in Active directory can be queried by using LDAP protocol

Q: what is the physical and logical structure of AD
Active directory physical structure is a hierarchal structure which fallows Forests—Trees—Domains—Child Domains—Grand Child—etc
Active directory is logically divided into 3 partitions
1.Configuration partition
2. Schema Partition
3. Domain partition
4. Application Partition (only in windows 2003 not available in windows 2000)
Out of these Configuration, Schema partitions can be replicated between the domain controllers in the in the entire forest. Where as Domain partition can be replicated between the domain controllers in the same domain
Q: what is DFS & its usage
DFS is a distributed file system used to provide common environment for users to access files and folders even when they are shared in different servers physically.
There are two types of DFS domain DFS and Stand alone DFS. We cannot provide redundancy for stand alone DFS in case of failure. Domain DFS is used in a domain environment which can be accessed by /domain name/root1 (root 1 is DFS root name). Stand alone DFS can be used in workgroup environment which can be accessed through /server name/root1 (root 1 is DFS root name). Both the cases we need to create DFS root ( Which appears like a shared folder for end users) and DFS links ( A logical link which is pointing to the server where the folder is physically shared)
The maximum number of Dfs roots per server is 1.
The maximum numbers of Dfs root replicas are 31.
The maximum number of Dfs roots per domain is unlimited.
The maximum number of Dfs links or shared folders in a Dfs root is 1,000

Q: what is RIS and what are its requirements
RIS is a remote installation service, which is used to install operation system remotely.
Client requirements
PXE DHCP-based boot ROM version 1.00 or later NIC, or a network adapter that is supported by the RIS boot disk.
Should meet minimum operating system requirements
Software Requirements
Below network services must be active on RIS server or any server in the network
Domain Name System (DNS Service)
Dynamic Host Configuration Protocol (DHCP)
Active directory “Directory” service





Q: Brief all the FSMO Roles
Domain Naming master and schema master are forest level roles. PDC emulator, Infrastructure master and RID master are Domain level roles; First server in the forest performs all 5 roles by default. Later we can transfer the roles

Domain Naming Master: Domain naming master is responsible for maintaining the relation ship between the domains. With out this role it is not possible to add or remove any domain.

Schema Master: Schema contains set of classes and attributes. eg User, computer, printer are the objects in AD which are having their own set of attributes.. Schema master is responsible for maintaining this schema. Changes to the schema will affect entire forest.

PDC Emulator: Server, which is performing this role, acts as a PDC in a mixed mode to synchronize directory information between windows 2000 DC to Windows NT BDC. Server, which is performing this role, will contain latest password information. This role is also responsible for time synchronization in the forest.

Infrastructure Master: It is responsible for managing group membership information in the domain. This role is responsible for updating DN when name or location of the object is modified.

RID Master: Server, which is performing this role, will provide pool of RID to other domain controllers in the domain. SID is the combination of SID and RID SID=SID+RID where SID is Security identifier common for all objects in the domain and RID is relative identifier unique for each object

Q: How to manually configure FSMO Roles to separate DC’s
We can configure manually by two ways
Through MMC
We can configure Domain Naming Master role through Active directory domains and trusts. We can configure Schema Master role through Active Directory schema. Other Three roles we can configure by Active directory users and computers
Through command promt
By using command NTDSUTIL—type ROLES—type CONNECTIONS—CONNECT TO SERVER SERVERNAME where server name is the name of the domain controller that you want to assign role---- Type transfer role, where role is the role that you want to transfer. For a list of roles that you can transfer, type ? at the fsmo maintenance prompt, and then press ENTER, or see the list of roles at the start of this article. For example, to transfer the RID master role, type transfer rid master. The one exception is for the PDC emulator role, whose syntax is transfer pdc, not transfer pdc emulator.

Q: What is the difference between authoritative and non-authoritative restore
In authoritative restore, Objects that are restored will be replicated to all domain controllers in the domain. This can be used specifically when the entire OU is disturbed in all domain controllers or specifically restore a single object, which is disturbed in all DC’s

In non-authoritative restore, Restored directory information will be updated by other domain controllers based on the latest modification time

Q: What is the difference between authoritative and non-authoritative restore

In authoritative restore, Objects that are restored will be replicated to all domain controllers in the domain. This can be used specifically when the entire OU is disturbed in all domain controllers or specifically restore a single object, which is disturbed in all DC’s

In non-authoritative restore, Restored directory information will be updated by other domain controllers based on the latest modification time.

Q: Difference between online and offline de-fragmentation
Online De-fragmentation will be performed by garbage collection process, which runs for every 12 hours by default which separate used space and white space (white space is the space created because of object deletion in AD eg User) and improves the efficiency of AD when the domain controller up and running

Offline defragmentation can be done manually by taking domain controller into Restoration mode. We can only reduce the file size of directory database where as the efficiency will be same as in online defragmentation

Q: What is tombstone period
Tombstones are nothing but objects marked for deletion. After deleting an object in AD the objects will not be deleted permanently. It will be remain 60 days by default (which can be configurable) it adds an entry as marked for deletion on the object and replicates to all DC’s. After 60 days object will be deleted permanently from all Dc’s.

Q: How to deploy the patches and what are the softwares used for this process

Using SUS (Software update services) server we can deploy patches to all clients in the network. We need to configure an option called “Synchronize with Microsoft software update server” option and schedule time to synchronize in server. We need to approve new update based on the requirement. Then approved update will be deployed to clients
We can configure clients by changing the registry manually or through Group policy by adding WUAU administrative template in group policy

Q: What is Clustering. Briefly define & explain it
Clustering is a technology, which is used to provide High Availability for mission critical applications. We can configure cluster by installing MCS (Microsoft cluster service) component from Add remove programs, which can only available in Enterprise Edition and Data center edition.

In Windows we can configure two types of clusters

NLB (network load balancing) cluster for balancing load between servers. This cluster will not provide any high availability. Usually preferable at edge servers like web or proxy.

Server Cluster: This provides High availability by configuring active-active or active-passive cluster. In 2 node active-passive cluster one node will be active and one node will be stand by. When active server fails the application will FAILOVER to stand by server automatically. When the original server backs we need to FAILBACK the application

Quorum: A shared storage need to provide for all servers which keeps information about clustered application and session state and is useful in FAILOVER situation. This is very important if Quorum disk fails entire cluster will fails

Heartbeat: Heartbeat is a private connectivity between the servers in the cluster,
which is used to identify the status of other servers in cluster

Q: What are the different types of partitions present in AD

Active directory is divided into three partitions
Configuration Partition—replicates entire forest
Schema Partition—replicates entire forest
Domain Partition—replicate only in domain
Application Partition (Only in Windows 2003)
An application directory partition is a directory partition that is replicated only to specific domain controllers. A domain controller that participates in the replication of a particular application directory partition hosts a replica of that partition. Only domain controllers running Windows Server 2003 can host a replica of an application directory partition.
Applications and services can use application directory partitions to store application-specific data. Application directory partitions can contain any type of object, except security principals. TAPI is an example of a service that stores its application-specific data in an application directory partition.
Application directory partitions are usually created by the applications that will use them to store and replicate data. For testing and troubleshooting purposes, members of the Enterprise Admins group can manually create or manage application directory partitions using the Ntdsutil command-line tool.
Q: What are the (two) services required for replication
File Replication Service (FRS)
Knowledge Consistency Checker (KCC)

Q: Can we use a Linux DNS Sever in 2000 Domain
We can use, But the BIND version should be 8 or greater

Q: What is ASR (Automated System Recovery) and how to implement it
ASR is a two-part system; it includes ASR backup and ASR restore. The ASR Wizard, located in Backup, does the backup portion. The wizard backs up the system state, system services, and all the disks that are associated with the operating system components. ASR also creates a file that contains information about the backup, the disk configurations (including basic and dynamic volumes), and how to perform a restore.

You can access the restore portion by pressing F2 when prompted in the text-mode portion of setup. ASR reads the disk configurations from the file that it creates. It restores all the disk signatures, volumes, and partitions on (at a minimum) the disks that you need to start the computer. ASR will try to restore all the disk configurations, but under some circumstances it might not be able to. ASR then installs a simple installation of Windows and automatically starts a restoration using the backup created by the ASR Wizard.

What are the different levels that we can apply Group Policy
We can apply group policy at SITE level---Domain Level---OU level

What is Domain Policy, Domain controller policy, Local policy and Group policy
Domain Policy will apply to all computers in the domain, because by default it will be associated with domain GPO, Where as Domain controller policy will be applied only on domain controller. By default domain controller security policy will be associated with domain controller GPO. Local policy will be applied to that particular machine only and effects to that computer only.
What is the use of SYSVOL folder
Policies and scripts saved in SYSVOL folder will be replicated to all domain controllers in the domain. FRS (File replication service) is responsible for replicating all policies and scripts
What is folder redirection?
Folder Redirection is a User group policy. Once you create the group policy and link it to the appropriate folder object, an administrator can designate which folders to redirect and where To do this, the administrator needs to navigate to the following location in the Group Policy Object:
User Configuration\Windows Settings\Folder Redirection
In the Properties of the folder, you can choose Basic or Advanced folder redirection, and you can designate the server file system path to which the folder should be redirected.

The %USERNAME% variable may be used as part of the redirection path, thus allowing the system to dynamically create a newly redirected folder for each user to whom the policy object applies.

What different modes in windows 2003 (Mixed, native & intrim….etc)
Different Active Directory features are available at different functional levels. Raising domain and forest functional levels is required to enable certain new features as domain controllers are upgraded from Windows NT 4.0 and Windows 2000 to Windows Server 2003
Domain Functional Levels: Windows 2000 Mixed mode, Windows 2000 Native mode, Windows server 2003 and Windows server 2003 interim ( Only available when upgrades directly from Windows NT 4.0 to Windows 2003)
Forest Functional Levels: Windows 2000 and Windows 2003

Ipsec usage and difference window 2000 & 2003.

Microsoft doesn’t recommend Internet Protocol security (IPSec) network address translation (NAT) traversal (NAT-T) for Windows deployments that include VPN servers and that are located behind network address translators. When a server is behind a network address translator, and the server uses IPSec NAT-T, unintended side effects may occur because of the way that network address translators translate network traffic
If you put a server behind a network address translator, you may experience connection problems because clients that connect to the server over the Internet require a public IP address. To reach servers that are located behind network address translators from the Internet, static mappings must be configured on the network address translator. For example, to reach a Windows Server 2003-based computer that is behind a network address translator from the Internet, configure the network address translator with the following static network address translator mappings:

• Public IP address/UDP port 500 to the server's private IP address/UDP port 500.
• Public IP address/UDP port 4500 to the server's private IP address/UDP port 4500.
These mappings are required so that all Internet Key Exchange (IKE) and IPSec NAT-T traffic that is sent to the public address of the network address translator is automatically translated and forwarded to the Windows Server 2003-based computer
Is it possible to do implicit transitive forest to forest trust relation ship in windows 2003?
Implicit Transitive trust will not be possible in windows 2003. Between forests we can create explicit trust
Two-way trust
One-way: incoming
One-way: Outgoing
GPMC & RSOP in windows 2003?
GPMC is tool which will be used for managing group policies and will display information like how many policies applied, on which OU’s the policies applied, What are the settings enabled in each policy, Who are the users effecting by these polices, who is managing these policies. GPMC will display all the above information.

RSoP provides details about all policy settings that are configured by an Administrator, including Administrative Templates, Folder Redirection, Internet Explorer Maintenance, Security Settings, Scripts, and Group Policy Software Installation.
When policies are applied on multiple levels (for example, site, domain, domain controller, and organizational unit), the results can conflict. RSoP can help you determine a set of applied policies and their precedence (the order in which policies are applied).

Assign & Publish the applications in GP & how?
Through Group policy you can Assign and Publish the applications by creating .msi package for that application
With Assign option you can apply policy for both user and computer. If it is applied to computer then the policy will apply to user who logs on to that computer. If it is applied on user it will apply where ever he logs on to the domain. It will be appear in Start menu—Programs. Once user click the shortcut or open any document having that extension then the application install into the local machine. If any application program files missing it will automatically repair.
With Publish option you can apply only on users. It will not install automatically when any application program files are corrupted or deleted.


How to use recovery console?
The Windows 2000 Recovery Console is a command-line console that you can start from the Windows 2000 Setup program. Using the Recovery Console, you can start and stop services, format drives, read and write data on a local drive (including drives formatted to use NTFS), and perform many other administrative tasks. The Recovery Console is particularly useful if you need to repair your system by copying a file from a floppy disk or CD-ROM to your hard drive, or if you need to reconfigure a service that is preventing your computer from starting properly. Because the Recovery Console is quite powerful, it should only be used by advanced users who have a thorough knowledge of Windows 2000. In addition, you must be an administrator to use the Recovery Console.

There are two ways to start the Recovery Console:
If you are unable to start your computer, you can run the Recovery Console from your Windows 2000 Setup disks or from the Windows 2000 Professional CD (if you can start your computer from your CD-ROM drive).
As an alternative, you can install the Recovery Console on your computer to make it available in case you are unable to restart Windows 2000. You can then select the Recovery Console option from the list of available operating systems
PPTP protocol for VPN in windows 2003?
Point-to-Point-Tunneling Protocol (PPTP) is a networking technology that supports multiprotocol virtual private networks (VPN), enableing remote users to access corporate networks securely across the Microsoft Windows NT® Workstation, Windows® 95, and Windows 98 operating systems and other point-to-point protocol (PPP)-enabled systems to dial into a local Internet service provider to connect securely to their corporate network through the Internet
What is a Stub zone and what is the use of it.
Stub zones are a new feature of DNS in Windows Server 2003 that can be used to streamline name resolution, especially in a split namespace scenario. They also help reduce the amount of DNS traffic on your network, making DNS more efficient especially over slow WAN links.
How to configure SNMP
SNMP can be configured by installing SNMP from Monitoring and Management tools from Add and Remove programs.
For SNMP programs to communicate we need to configure common community name for those machines where SNMP programs (eg DELL OPEN MANAGER) running. This can be configured from services.msc--- SNMP service -- Security
what is the use of LDAP (X.500 standard?)
LDAP is a directory access protocol, which is used to exchange directory information from server to clients or from server to servers
what are the problems that are generally come across DHCP
Scope is full with IP addresses no IP’s available for new machines
If scope options are not configured properly eg default gateway
Incorrect creation of scopes etc

what is the role responsible for time synchronization
PDC Emulator is responsible for time synchronization. Time synchronization is important because Kerberos authentication depends on time stamp information

what is TTL & how to set TTL time in DNS
TTL is Time to Live setting used for the amount of time that the record should remain in cache when name resolution happened.
We can set TTL in SOA (start of authority record) of DNS
How to take DNS and WINS,DHCP backup
%System root%/system32/dns
%System root%/system32/WINS
%System root%/system32/DHCP
Difference between inter-site and intra-site replication. Protocols using for replication.
Intra-site replication can be done between the domain controllers in the same site. Inter-site replication can be done between two different sites over WAN links
BHS (Bridge Head Servers) is responsible for initiating replication between the sites. Inter-site replication can be done B/w BHS in one site and BHS in another site.
We can use RPC over IP or SMTP as a replication protocols where as Domain partition is not possible to replicate using SMTP

How to monitor replication
We can user Replmon tool from support tools
what is the difference between Authorized DHCP and Non Authorized DHCP
To avoid problems in the network causing by mis-configured DHCP servers, server in windows 2000 must be validate by AD before starting service to clients. If an authorized DHCP finds any DHCP server in the network it stop serving the clients
what is the use of terminal services
Terminal services can be used as Remote Administration mode to administer remotely as well as Application Server Mode to run the application in one server and users can login to that server to user that application.
what is the protocol used for terminal services
RDP
what is the port number for RDP
3389

What are the port numbers?
FTP-21, Telnet – 23, HTTP-80, SMTP-25, TFTP-69, TCP-6, UDP-17, DNS-53, Kerberos-88, LDAP-389, DHCP-67, 68, IP V6-41, RIP-520, ICMP-1, IGRP-9,
Global Catalog-3268, Pop3-110, Terminal Server-RDP-3389

what are the different types of profiles in 2000
Local Profiles
Roaming profiles
Mandatory Profiles
Features of windows2003 ACTIVE DIRECTORY

Easier Deployment and Management

ADMT version 2.0—migrates password from NT4 to 2000 to 20003 or from 2000 to 2003
Domain Rename--- supports changing Domain Name System and/or NetBios name
Schema Redefine--- Allows deactivation of attributes and class definitions in the Active directory schema
AD/AM--- Active directory in application mode is a new capability of AD that addresses certain deployment scenarios related to directory enabled applications
Group Policy Improvements----introduced GPMC tool to manage group policy
UI—Enhanced User Interface
Grater Security
Cross-forest Authentication
Cross-forest Authorization
Cross-certification Enhancements
IAS and Cross-forest authentication
Credential Manager
Software Restriction Policies
Improved Performance and Dependability
Easier logon for remote offices
Group Membership replication enhancements
Application Directory Partitions
Install Replica from media
Dependability Improvements--- updated Inter-Site Topology Generator (ISTG) that scales better by supporting forests with a greater number of sites than Windows 2000.
FILE AND PRINT SERVICES
Volume shadow copy service
NTFS journaling file system
EFS
Improved CHDSK Performance
Enhanced DFS and FRS
Shadow copy of shared folders
Enhanced folder redirection
Remote document sharing (WEBDAV)
IIS
Fault-tolerant process architecture----- The IIS 6.0 fault-tolerant process architecture isolates Web sites and applications into self-contained units called application pools
Health Monitoring---- IIS 6.0 periodically checks the status of an application pool with automatic restart on failure of the Web sites and applications within that application pool, increasing application availability. IIS 6.0 protects the server, and other applications, by automatically disabling Web sites and applications that fail too often within a short amount of time

Automatic Process Recycling--- IIS 6.0 automatically stops and restarts faulty Web sites and applications based on a flexible set of criteria, including CPU utilization and memory consumption, while queuing requests
Rapid-fail Protection---- If an application fails too often within a short amount of time, IIS 6.0 will automatically disable it and return a "503 Service Unavailable" error message to any new or queued requests to the application