Cisco 642-902 Online Practice Questions and Exam Preparation

Cisco 642-902 Online Questions & Answers

• Question 51:

  You have implemented mutual route redistribution between OSPF and EIGRP on a border router. When checking the routing table on one of the EIGRP routers within the EIGRP routing domain, you are seeing some, but not all of the expected routes. What should you verify to troubleshoot this problem?

  A. The border router is using a proper seed metric for OSPF.
  B. The border router is using a proper seed metric for EIGRP.
  C. The administrative distance is set for OSPF and EIGRP.
  D. The missing OSPF routes are present in the routing table of the border router.
  E. The subnet keyword on the border router in the redistribute OSPF command.
  D. The missing OSPF routes are present in the routing table of the border router.

  ---

  We are checking the routing table on EIGRP routers not OSPF so we don't need to check the seed metric for OSPF. Besides OSPF doesn't need to specify seed metric as all external routes get a default metric of 20 (except for BGP, which is

  1).

  We must specify seed metrics when redistributing into EIGRP (and RIP). If not all the redistributed routes will not be seen but the question says only some routes are missing.

  The default administrative distance for external routes redistributed into EIGRP is 170 so we don't need to set it .

  The sunbet keyword is only used when redistributing into OSPF, not to other routing protocols .

  We should check the routing table of the border router to see the missing OSPF routes are there or not. An incorrect distribute-list can block some routes and we can't see it in other EIGRP routers.

• Question 52:

  Which routing protocol will continue to receive and process routing updates from neighbors after the passive interface router configuration command is entered?

  A. EIGRP
  B. RIP
  C. OSPF
  D. IS-IS
  B. RIP

  ---

  Reference: http://www.routeralley.com/ra/docs/rip.pdf

• Question 53:

  Refer to the exhibit.

  

  Network 10.0.0.0/8 is being advertised to autonomous system 65550 via both external links. Which statement about the preferred path to the 10.0.0.0/8 network is true?

  A. Router R1 will be preferred because its neighbor has the higher autonomous system number.
  B. Router R1 will be preferred because it has the lower neighbor IP address.
  C. Router R1 will be preferred because it has a lower local preference.
  D. Router R2 will be preferred because its neighbor has a lower autonomous system number.
  E. Router R2 will be preferred because it has the higher neighbor IP address.
  F. Router R2 will be preferred because it has a higher local preference.
  F. Router R2 will be preferred because it has a higher local preference.

  ---

  The preferred path to 10.0.0.0/8 network is R2 because it has a higher local preference. The following process summarizes how BGP chooses the best route on a Cisco router. Prefer the route with the highest weight. (The weight attribute is proprietary to Cisco and is local to the router only.) If multiple routes have the same weight, prefer the route with the highest local preference value. (The local preference is used within an autonomous system.) If multiple routes have the same local preference, prefer the route that the local router originated. A locally originated route has a next hop of 0.0.0.0 in the BGP table. If none of the routes were locally originated, prefer the route with the shortest autonomous system path. If the autonomous system path length is the same, prefer the lowest origin code (IGP < EGP < incomplete). If all origin codes are the same, prefer the path with the lowest MED. (The MED is exchanged between autonomous systems.) The MED comparison is made only if the neighboring autonomous system is the same for all routes considered, unless the bgp always-compare-med command is enabled If the routes have the same MED, prefer external paths to internal paths. If synchronization is disabled and only internal paths remain, prefer the path through the closest IGP neighbor, which means that the router prefers the shortest internal path within the autonomous system to reach the destination (the shortest path to the BGP next hop). For EBGP paths, select the oldest route to minimize the effect of routes going up and down (flapping). Prefer the route with the lowest neighbor BGP router ID value. If the BGP router IDs are the same, prefer the router with the lowest neighbor IP address.

  In this example, since the weights remained the same (default) value the next thing that is looked at is the highest local preference.

• Question 54:

  Refer to the exhibit.

  

  R1 and R2 belong to the RIP routing domain that includes the networks 10.20.0.0/16 and 10.21.0.0/16. R3 and R4 are performing two-way route redistribution between OSPF and RIP. A network administrator has discovered that R2 is

  receiving OSPF routes for the networks 10.20.0.0/16 and 10.21.0.0/16 and a routing loop has occurred.

  Which action will correct this problem?

  A. Apply an inbound ACL to the R2 serial interface.
  B. Change the RIP administrative distance on R3 to 110.
  C. Configure distribute-lists on R3 and R4.
  D. Set the OSPF default metric to 20.
  E. Change the OSPF administrative distance on R3 to 110.
  C. Configure distribute-lists on R3 and R4.

  ---

  Distribute List is Like an access-list, use to deny or permit the routing update to pass through a router/interface. Distribute List allow you apply an access list to a routing updates.

  It can be apply on in or out bond of an interface under a routing process. e.g in fig. R1 want to send a routing update to it neighbor, this update will go through from interface S0/0, router will check, is there some Distribute List apply to this interface. If there is a Distribute List which would contain the allow route to pass through this interface.

• Question 55:

  Refer to the exhibit. During the process of configuring a virtual link to connect area 2 with the backbone area, the network administrator received this console message on R3:

  *Mar 1 00:25:01.084: %OSPF-4-ERRRCV: Received invalid packet: mismatch area ID, from backbone area must be virtual link but not found from 20.20.20.1, Serial 0 How should the virtual link be configured on the OSPF routers to establish

  full connectivity between the areas?

  

  A. R1(config-router)# area 1 virtual-link 30.30.30.3 R3(config-router)# area 1 virtual-link 20.20.20.1
  B. R1(config-router)# area 1 virtual-link 20.20.20.2 R3(config-router)# area 1 virtual-link 30.30.30.2
  C. R1(config-router)# area 0 virtual-link 1.1.1.1 R3(config-router)# area 2 virtual-link 3.3.3.3
  D. R1(config-router)# area 1 virtual-link 3.3.3.3 R3(config-router)# area 1 virtual-link 1.1.1.1
  E. R1(config-router)# area 1 virtual-link 2.2.2.2 R3(config-router)# area 1 virtual-link 2.2.2.2
  D. R1(config-router)# area 1 virtual-link 3.3.3.3 R3(config-router)# area 1 virtual-link 1.1.1.1

  ---

  When designing a multi-area OSPF network, all areas should be connected to the backbone area. However, there may be instances when an area will need to cross another area to reach the backbone area like area 2 in this case. A virtual link has the following two requirements:

  + It must be established between two routers that share a common area and are both ABRs. + One of these two routers must be connected to the backbone.

  In this case, two routers that satisfy the above requirements are R1 and R3. The syntax for creating a virtual link across an area is:

  Area virtual-link

  The area-id is the number of the transit area, in this example Area 1 and neighbor-router-id is the IP address of the highest loopback interface configured or can be manually set on the neighboring router.

• Question 56:

  Refer to the exhibit.

  

  The Route.com company is running EIGRP between all the routers. Currently, if one of the LAN links (LAN1 or LAN2) at the headquarters flaps (goes up and down), the HQ-RTR1 and HQ-RTR2 routers will experience high CPU usage and have a long EIGRP convergence time. As the new network administrator, you are asked to investigate this situation and determine if there is a quick way to resolve this issue. Which is the most important thing that you can quickly verify first to resolve this issue?

  A. Verify that the bandwidth setting on all WAN links is correct.
  B. Verify that the HQ-RTR1 and HQ-RTR2 routers are configured to send only a default route to all the spoke routers.
  C. Verify that the HQ-RTR1 and HQ-RTR2 routers are configured for EIGRP Nonstop Forwarding.
  D. Verify that all the spoke routers are configured for auto summarization.
  E. Verify that all the spoke routers are configured as EIGRP stub.
  E. Verify that all the spoke routers are configured as EIGRP stub.

  ---

  Stub routing is commonly used in a hub and spoke network topology. In a hub and spoke network, one or more end (stub) networks are connected to a remote router (the spoke) that is connected to one or more distribution routers (the hub). The remote router is adjacent only to one or more distribution routers. The only route for IP traffic to follow into the remote router is through a distribution router. This type of configuration is commonly used in WAN topologies where the distribution router is directly connected to a WAN. The distribution router can be connected to many more remote routers. Often, the distribution router will be connected to 100 or more remote routers. In a hub and spoke topology, the remote router must forward all nonlocal traffic to a distribution router, so it becomes unnecessary for the remote router to hold a complete routing table. Generally, the distribution router need not send anything more than a default route to the remote router.

  When using the EIGRP Stub Routing feature, you need to configure the distribution and remote routers to use EIGRP, and to configure only the remote router as a stub. Only specified routes are propagated from the remote (stub) router. The router responds to queries for summaries, connected routes, redistributed static routes, external routes, and internal routes with the message "inaccessible." A router that is configured as a stub will send a special peer information packet to all neighboring routers to report its status as a stub router.

  Any neighbor that receives a packet informing it of the stub status will not query the stub router for any routes, and a router that has a stub peer will not query that peer. The stub router will depend on the distribution router to send the proper updates to all peers.

  Reference: http://www.cisco.com/en/US/docs/ios/12_0s/feature/guide/eigrpstb.html

• Question 57:

  Which two statements about the EIGRP DUAL process are correct? (Choose two.)

  A. An EIGRP route will go active if there are no successors or feasible successors in the EIGRP topology table.
  B. An EIGRP route will go passive if there are no successors in the EIGRP topology table.
  C. DUAL will trigger an EIGRP query process while placing the flapping routes in the holddown state.
  D. A feasible successor in the EIGRP topology table can become the successor only after all the query requests have been replied to.
  E. The stuck in active state is caused when the wait for the query replies have timed out.
  F. EIGRP queries are sent during the loading state in the EIGRP neighbor establishment process.
  A. An EIGRP route will go active if there are no successors or feasible successors in the EIGRP topology table.
  E. The stuck in active state is caused when the wait for the query replies have timed out.

  ---

  Reference: http://routemyworld.com/category/routing-protocols/eigrp/

• Question 58:

  During the redistribution process configured on RTA, some of the EIGRP routes, such as 10.1.1.0/24 and 10.2.2.0/24, are not being redistributed into the OSPF routing domain.

  

  Which two items could be a solution to this problem? (Choose two.)

  A. Change the metric-type to 2 in the redistribute command.
  B. Configure the redistribute command under router eigrp 1 instead.
  C. Change the EIGRP AS number from 100 to 1 in the redistribute command.
  D. Add the subnets option to the redistribute command.
  E. Change the metric to an EIGRP compatible metric value (bandwidth, delay, reliability, load, MTUs) in the redistribute command.
  C. Change the EIGRP AS number from 100 to 1 in the redistribute command.
  D. Add the subnets option to the redistribute command.

  ---

  In this example, the router is configured for EIGRP AS 1, but EIGRP AS 100 is being redistributed into OSPF so the EIGRP AS needs to be changed from 100 to 1. The subnets keyword tells OSPF to redistribute all subnet routes. Without the subnets keyword, only networks that are not subnetted are redistributed by OSPF.

  Example: RTA(config)#router ospf 109 RTA(config-router)#redistribute rip subnets RTA(config-router)#network 130.10.62.0 0.0.0.255 area 0 RTA(config-router)#network 130.10.63.0 0.0.0.255 area 0 The subnets keyword tells OSPF to redistribute all subnet routes. Without the subnets keyword, only networks that are not subnetted are redistributed by OSPF.

• Question 59:

  Refer to the exhibit.

  

  Which two statements are true about the partial configuration that is provided? (Choose two.)

  A. All the configured neighbors are in autonomous system 100.
  B. The peer group shortens the IBGP configuration.
  C. The peer group shortens the EBGP configuration.
  D. Only the outgoing filters are applied to BGP updates.
  E. Three AS-path filters are applied to each BGP neighbor.
  A. All the configured neighbors are in autonomous system 100.
  B. The peer group shortens the IBGP configuration.

  ---

  This is an IBGP peer group because the AS numbers in "router bgp {AS number}" and "neighbor internal remote-as {AS number} are the same.

  A BGP peer group reduces the load on system resources by allowing the routing table to be checked only once, and updates to be replicated to all peer group members instead of being done individually for each peer in the peer group. In

  addition, a BGP peer group also simplifies the BGP configuration.

  This is the process of creating a peer-group (used the output above):

  

  Just one thing to notice is the last command "neighbor 171.69.232.55 filter-list 3 in" indicates the filter-list 3 will be applied for neighbor 171.69.232.55 while other neighbors will be applied filter-list 2 as the inbound filter-list (all neighbors use outbound filter-list 1).

• Question 60:

  Above is the output from show ip bgp neighbors command.

  

  What is line 21 stating about the BGP connection?

  A. the number of neighbors that the router has
  B. the number of times the router has established a TCP connection
  C. the number of consecutive TCP connections to the specified remote neighbor
  D. the number of total TCP connections that the router has
  B. the number of times the router has established a TCP connection

  ---

  According to http://www.cisco.com/en/US/docs/ios/12_3/iproute/command/reference/ip2_s2g.html#wp104 0913, "Connections established" is the number of times a TCP and BGP connection have been successfully established while "dropped" is the number of times that a valid session has failed or been taken down.