Cisco 642-902 Online Practice Questions and Exam Preparation

Cisco 642-902 Online Questions & Answers

• Question 101:

  Which functionality is required within an IP router that is situated at the boundary of an IPv4 network and an IPv6 network to allow communication between IPv6-only and IPv4-only nodes?

  A. Autoconfiguration
  B. Automatic 6to4 Tunnel
  C. Automatic 6to4 Relay
  D. Network Address Translator-Protocol Translator (NAT-PT)
  E. Intrasite Automatic Tunnel Address Protocol (ISATAP)
  D. Network Address Translator-Protocol Translator (NAT-PT)

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  Reference:

  http://www.cisco.com/en/US/prod/collateral/iosswrel/ps8802/ps6969/ps1835/prod_white_pap er09186a008011ff51.html (Introduction, see 4th para)

• Question 102:

  Refer to the exhibit.

  

  BigBids Incorporated is a worldwide auction provider. The network uses EIGRP as its routing protocol throughout the corporation. The network administrator does not understand the convergence of EIGRP. Using the output of the show ip eigrp topology all-links command, answer the administrator's question.

  Which two networks does the Core1 device have feasible successors for? (Choose two)

  A. 172.17.0.0/30
  B. 172.17.1.0/24
  C. 172.17.2.0/24
  D. 172.17.3.0/25
  E. 172.17.3.128/25
  F. 10.140.0.0/24
  A. 172.17.0.0/30
  F. 10.140.0.0/24

  ---

  To understand the output of the "show ip eigrp topology all-links command" command, let's analyze an entry (we choose the second entry because it is better for demonstration than the first one)

  

  The first line tells us there is only 1 successor for the path to 10.140.0.0/24 network but there are 2 lines below. So we can deduce that one line is used for successor and the other is used for another route to that network. Each of these two lines has 2 parameters: the first one ("156160 or "157720) is the Feasible Distance (FD) and the second ("128256 or "155160) is the Advertised Distance (AD) of that route.

  The next thing we want to know is: if the route via 172.17.10.2 (the last line) would become the feasible successor for the 10.140.0.0/24 network. To figure out, we have to compare the Advertised Distance of that route with the Feasible Distance of the successor's route, if AD < FD then it will become the feasible successor. In this case, because AD (155160) < FD (156160) so it will become the feasible successor. Therefore we can conclude the network 10.140.0.0/24 has 1 feasible successor.

  Because the question asks about feasible successor so we just need to focus on entries which have more paths than the number of successor. In this case, we find 3 entries that are in blue boxes because they have only 1 successor but has 2 paths, so the last path can be the feasible successor.

  By comparing the value of AD (of that route) with the FD (of successor's route) we figure out there are 2 entries will have the feasible successor: the first and the second entry. The third entry has AD = FD (30720) so we eliminate it.

• Question 103:

  Refer to the topology diagram.

  

  R3 is redistributing the EIGRP routes into OSPF. What will the EIGRP routes appear as in the routing table of R1?

  A. O
  B. O IA C. O E2
  D. D
  E. D EX
  C

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  Reference: http://netpxel.com/wiki2/doku.php/ospf-eigrp-route-redistribution

• Question 104:

  Which three route filtering statements are true? (Choose three)

  A. After the router rip and passive-interface s0/0 commands have been issued, the s0/0 interface will not send any RIP updates, but will receive routing updates on that interface.
  B. After the router eigrp 10 and passive-interface s0/0 commands have been issued, the s0/0 interface will not send any EIGRP updates, but will receive routing updates on that interface
  C. After the router ospf 10 and passive-interface s0/0 commands have been issued , the s0/0 interface will not send any OSPF updates, but will receive routing updates on that interface
  D. When you use the passive-interface command with RIPv2, multicasts are sent out the specified interface
  E. When you use the passive-interface command with EIGRP, hello messages are not sent out the specified interface
  F. When you use the passive-interface command with OSPF, hello messages are not sent out the specified interface
  A. After the router rip and passive-interface s0/0 commands have been issued, the s0/0 interface will not send any RIP updates, but will receive routing updates on that interface.
  E. When you use the passive-interface command with EIGRP, hello messages are not sent out the specified interface
  F. When you use the passive-interface command with OSPF, hello messages are not sent out the specified interface

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  Passive-interface command is used in all routing protocols to disable sending updates out from a specific interface. However the command behavior varies from o ne protocol to another"

  - In RIP, this command will not allow sending multicast updates via a specific interface but will allow listening to incoming updates from other RIP speaking neighbors. This means that the router will still be able to receive updates o n that passive interface and use them in its routing table. In EIGRP and OSPF the passive-interface command stops sending outgoing hello packets, hence the router can not form any neighbor relationship via the passive interface. This behavior stops both outgoing and incoming routing updates.

• Question 105:

  Click and drag the associated EIGRP functionality on the left to the corresponding topology characteristic on the right.

  Select and Place:

  

  

• Question 106:

  For a GRE tunnel to be up between two routers, which of the following must be configured?

  A. Loopback Interface
  B. IP reachability between the loopback interfaces
  C. Dynamic Routing between routers.
  D. Tunnel interfaces must be in the same subnet.
  D. Tunnel interfaces must be in the same subnet.

  ---

  Reference: GRE tunnels don't require loopbacks. They work quite well using physical interfaces as the source and destination. They also don't require dynamic routing; static routes work just fine. Place the IP addresses assigned to the tunnels in different subnets and there won't be any connectivity over the tunnels... that is unless you place static routes at both endpoints pointing to the remote tunnel IP address via the tunnel. Host routes work just fine.

• Question 107:

  A network administrator has enabled OSPF across an NBMA network and has issued the command ip ospf network nonbroadcast. Given those facts, which two statements are true? (Choose two.)

  A. DR and BDR elections will occur.
  B. DR and BDR elections will not occur.
  C. All routers must be configured in a fully meshed topology with all other routers.
  D. The neighbor command is required to build adjacencies.
  E. Interfaces will automatically detect and build adjacencies with neighbor routers.
  A. DR and BDR elections will occur.
  D. The neighbor command is required to build adjacencies.

  ---

  Even if there is only one router, broadcast multiaccess networks elect a DR and a BDR to serve as focal points for routing information. In contrast, point- to-point OSPF networks do not elect a DR because they can never include more than

  two nodes.

  Another type of OSPF network, Nonbroadcast Multiaccess (NBMA), can include more than two nodes. Therefore, NBMA will try to elect a DR and a BDR. Common NBMA implementations include Frame Relay, X.25, and SMDS. NBMA

  networks follow rules at Layer 2 that prevent the delivery of broadcasts and multicasts.

  A non-broadcast environment requires that all OSPF neighbors be manually configured. This is the default setting for physical interfaces with Frame Relay encapsulation, as well as for their point-to-multipoint subinterfaces. By manually

  configuring each neighbor, OSPF knows exactly which neighbors need to participate and which neighbor is identified as the DR. Also, communication between neighbors is done via unicast instead of multicast. This configuration also requires

  a full mesh and has the same weakness as the broadcast environment.

  For non-broadcast networks the default Hello interval is 30 seconds and the Dead interval is four times the Hello interval, 120 seconds. Non-broadcast multi-access networks do elect a DR and BDR, due to their multi-access nature. In order

  to set which router you want as the DR, you must set the priority in the neighbor statement to elect the neighbor as the DR. In order to manually configure who your neighbors are, the following command must be entered in router

  configuration mode for the selected OSPF process:

  neighbor ip_address

  ip_address = the ip address of the neighbor.

  If you would like to set the priority of this router to become the DR, you will need to append the priority of the neighbor:

  neighbor ip_address priority value

• Question 108:

  Which command displays the IBGP and EBGP neighbors that are configured?

  A. show ip bgp
  B. show ip bgp paths
  C. show ip bgp peers
  D. show ip bgp summary
  D. show ip bgp summary

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  The picture below shows the output of the show ip bgp summary

  

  Notice that the "show ip bgp" command to display BGP topology database. Below is the output of the "show ip bgp" command:

  

• Question 109:

  What are three key concepts that apply when configuring the EIGRP stub routing feature in a hub and spoke network? (Choose three.)

  A. A hub router prevents routes from being advertised to the remote router.
  B. Only remote routers are configured as stubs.
  C. Stub routers are not queried for routes.
  D. Spoke routers connected to hub routers answer the route queries for the stub router.
  E. A stub router should have only EIGRP hub routers as neighbors.
  F. EIGRP stub routing should be used on hub routers only.
  B. Only remote routers are configured as stubs.
  C. Stub routers are not queried for routes.
  E. A stub router should have only EIGRP hub routers as neighbors.

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  Reference: http://astorinonetworks.com/2011/06/14/eigrp-stub-routing/ http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/eigrpstb.html

• Question 110:

  Refer to the partial configurations in the exhibit.

  

  What address is utilized for DR and BDR identification on Router1?

  A. the configured router-id address
  B. an arbitrarily generated internal address
  C. the sequential 1/1 address
  D. the sequential 2/0 address
  A. the configured router-id address

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  The point of this question is DR and BDR election of OSPFv3.

  OSPF test the title of the DR and BDR election.

  DR and BDR election there are two standards:

  1.

  Interface priority, the default is 1.

  2.

  Router-iD. manually specify> Highest loopback interface> Highest active IP address This title, there is no priority list, it is the default, manually specify the Router-iD. 10.1.1.3, so hand-Router-id specified in the election has become the standard DR and BDR. The selection of DR and BDR is the same between OSPFv2 and OSPFv3.