Cisco 642-902 Online Practice Questions and Exam Preparation

Cisco 642-902 Online Questions & Answers

• Question 81:

  Refer to the exhibit. What two statements are true? (Choose two.)

  

  A. Interface FastEthernet 0/0 was configured with the ipv6 ospf 1 area 1 command.
  B. OSPF version 2 has been enabled to support IPv6.
  C. The IP address of the backup designated router (BDR) is FE80::205:5FFF:FED3:5808.
  D. The output was generated by the show ip interface command.
  E. The router was configured with the commands: router ospf 1 network 172.16.6.0 0.0.0.255 area 1
  F. This is the designated router (DR) on the FastEthernet 0/0 link.
  A. Interface FastEthernet 0/0 was configured with the ipv6 ospf 1 area 1 command.
  C. The IP address of the backup designated router (BDR) is FE80::205:5FFF:FED3:5808.

  ---

  OSPFv3 supports IPv6. The configuration of OSPFv3 is not a subcommand mode of the router ospf command as it is in OSPFv2 configuration. For example, instead of using the network area command to identify networks that are part of the OSPFv3 network, the interfaces are directly configured to specify that IPv6 networks are part of the OSPFv3 network.

  The following describes the steps to configure OSPF for IPv6:

  

  There are several commonly used OSPFv3 show commands, including the show ipv6 ospf [process-id] [area-id] interfacee [interface] command.

• Question 82:

  A stub area is typically created using what kind of topology?

  A. Broadcast
  B. Point-to-point
  C. Hub and spoke
  D. Full Mesh
  C. Hub and spoke

  ---

  A stub area is typically created when you have a hub-and-spoke topology, with the spoke being the stub area, such as a branch office. In this case, the branch office does not need to know about every network at the headquarters site; instead, it can use a default route to get there.

• Question 83:

  Which two reductions are the correct reductions of the IPv6 address 2001:0d02:0000:0000:0014:0000:0000:0095? (Choose two)

  A. 2001:0d02:::0014:::0095
  B. 2001:d02::14::95
  C. 2001:d02:0:0:14::95
  D. 2001:d02::14:0:0:95
  C. 2001:d02:0:0:14::95
  D. 2001:d02::14:0:0:95

  ---

  We can't use triple colons (:::) in IPv6 presentation. Also We can't use double colons (::) twice. You can use it only once in any address because if two double colons are placed in the same address, there will be no way to identify the size of each block of 0s. Remember the following techniques to shorten an IPv6 address:

  -

  Omit leading 0s in the address field, so :0000 can be compressed to just :0 and :0d02 can be com- pressed to :d02 (but :1d00 can not be compressed to :1d)

  -

  Use double colons (::), but just once, to represent a contiguous block of 0s, so 2001:0d02:0000:0000:0014:0000:0000:0095 can be compressed to 2001:0d02::14:0:0:95 or 2001:0d02:0:0:14::95

• Question 84:

  Refer to the exhibit.

  

  By default, when RTB passes BGP advertisements from RTA about network 192.168.2.0 to RTC, what address will be listed as the next-hop address? Select the best response

  A. 192.168.1.49
  B. 10.1.1.1
  C. 10.1.1.2
  D. 192.168.1.50
  D. 192.168.1.50

  ---

  The next hop attribute is a well-known mandatory attribute, type code 3. In terms of an IGP, such as RIP, the "next hop" to reach a route is the IP address of the router that has announced the route.

  The next hop concept with BGP is more complex and takes one of the following three forms:

  For EBGP sessions, the next hop is the IP address of the neighbor that announced the route. For IBGP sessions, where routes originated inside the AS, the next hop is the IP address of the neighbor that announced the route. For routes

  injected into the AS by way of EBGP, the next hop learned from EBGP is carried unaltered into IBGP. The next hop is the IP address of the EBGP neighbor from which the route was learned. When the route is advertised on a multiaccess

  medium, such as Ethernet or Frame Relay, the next hop is usually the IP address of the interface of the router. This will be the interface connected to the media that originated the route.

• Question 85:

  What are two rules for compacting IPv6 addresses? (Choose two.)

  A. Every 16-bit segment segment that consists of all zeroes can be represented with a single colon.
  B. The trailing zeroes in any 16-bit segment do not have to be written.
  C. The leading zeroes in any 16-bit segment do not have to be written.
  D. Any single, continuous string of one or more 16-bit segments that consists of all zeroes can be represented with a double colon.
  E. The maximum number of times a double colon can replace a 16-bit segment that consists of all zeroes is two.
  F. Two zeroes in the middle of any 16-bit segment do not have to be written.
  C. The leading zeroes in any 16-bit segment do not have to be written.
  D. Any single, continuous string of one or more 16-bit segments that consists of all zeroes can be represented with a double colon.

  ---

  Reference: http://www.9tut.com/ipv6-tutorial

• Question 86:

  (OSPF Sim)

  OSPF is configured on routers Amani and Lynaic. Amani's S0/0 interface and Lynaic's S0/1 interface are in Area 0. Lynaic's Loopback0 interface is in Area 2.

  

  Your task is to configure the following:

  Portland's S0/0 interface in Area 1

  Amani's S0/1 interface in Area 1

  Use the appropriate mask such that ONLY Portland's S0/0 and Amnani's S0/1 could be in Area 1. Area 1 should not receive any external or inter-area routes (except the default route).

  Check the answer below

  First, we configure Portland's S0/0 interface so that it belongs to Area 1. So, we have to find out which subnetwork the IP address 192.168.4.5/30 (the IP of interface S0/0 of Portland) belongs to. This address belongs to a subnetwork which has: Increment: 4 (/30 = 255.255.255.252 or 1111 1111.1111 1111.1111 1111.1111 1100) Network address: 192.168.4.4 (because 4 = 4 * 1 and 4 < 5) Broadcast address: 192.168.4.7 (because 7 = 4 + 4 - 1) (It is not necessary to find out the broadcast address but we should know it) The question requires that only Portland's S0/0 and Amani's S0/1 could be in Area 1, therefore we must use a wildcard of 0.0.0.3 (this wildcard is equivalent with a subnet mask of /30) so that there are only 2 IP addresses can participate in area 1 (they are 192.168.4.5 and 192.168.4.6). The full command we use here is network 192.168.4.4 0.0.0.3 area 1 The question also requires that "Area 1 should not receive any external or inter-area routes (except the default route)". Recall that if we don't want the router to receive external routes, we have to stop LSA Type 5. And if we don't want to receive inter-area routes, we have to stop LSA Type 3 and Type 4. Therefore we have to configure area 1 as a totally stubby area. For your information, here is the definition of a totally stubby areA. "Totally stubb area - This area does not accept summary LSAs from other areas (types 3 or 4) or external summary LSAs (Type 5). Types 3,4 and 5 LSAs are replaced by the Area Border Router(ABR) with a default router. Totally stubby areas protect internal routers by minimizing the routing table and summarizing everything outside the area with a default route." (CCNP BSCI Official Exam Certification Guide, Fourth Edition) In conclusion, we have to configure area 1 as a totally stubby area. We do that by configuring Portland as stub and configuring Amani (ABR router) as a stub + "no-summary"suffix. + Configure Portland router as a stub: Portland#configure terminal Portland(config)#router ospf 1 Allow network 192.168.4.4/30 to join Area 1, notice that you have to convert subnet mask into wildcard mask: Portland(config-router)#network 192.168.4.4 0.0.0.3 area 1 Configure Portland as a stub: Portland(config-router)#area 1 stub Portland(config-router)#end Portland#copy running-config startup-config

  + Configure Amani router as a "totally stub": Amani#configure terminal Amani(config)#router ospf 1 Amani(config-router)#network 192.168.4.4 0.0.0.3 area 1 Make area 1 become a totally stubby area, notice that we can only use this command on ABR router: Amani(config-router)#area 1 stub no-summary Amani(config-router)#end Amani#copy running-config startup-config

• Question 87:

  Refer to the exhibit.

  

  How would you confirm on R1 that load balancing is actually occurring on the default- network (0.0.0.0)?

  A. Use ping and the show ip route command to confirm the timers for each default network resets to 0.
  B. Load balancing does not occur over default networks; the second route will only be used for failover.
  C. Use an extended ping along with repeated show ip route commands to confirm the gateway of last resort address toggles back and forth.
  D. Use the traceroute command to an address that is not explicitly in the routing table.
  D. Use the traceroute command to an address that is not explicitly in the routing table.

  ---

  The most simple method to test load balancing is to use the "traceroute" command. If load balancing is working correctly, we will see different paths to reach the destination each time we use that command. Unknown address will be routed via the default-network 0.0.0.0 so we must use an address that is not explicitly in the routing table.

• Question 88:

  What does the command clear ipv6 ospf process accomplish?

  A. The OSPF adjacencies are cleared and initiated again.
  B. The route table is cleared. Then the OSPF neighbors are reformed.
  C. The shortest path first (SPF) algorithm is performed on the LSA database.
  D. The OSPF database is repopulated. Then the shortest path first (SPF) algorithm is performed.
  D. The OSPF database is repopulated. Then the shortest path first (SPF) algorithm is performed.

  ---

  The command "clear ipv6 ospf" will clear the present routing table and force the OSPFv3 process to build a new one. This command is often used when something in the network was changed or for debugging purpose. When the "process" keyword is added, which means "clear ipv6 ospf process", the OSPF database is cleared and repopulated then the SPF algorithm is performed.

• Question 89:

  Which command must be globally enabled on a Cisco router to support IPv6?

  A. ip routing ipv6
  B. ipv6 unicast-routing
  C. ipv6 routing
  D. ip classless
  E. ipv6 cef
  B. ipv6 unicast-routing

  ---

  Reference: http://computernetworkingnotes.com/ipv6-features-concepts-and- configurations/routing-with-ipv6.html (See the first para)

• Question 90:

  Based on the exhibited output,

  

  Which three statements are true? (Choose three.)

  A. R1 is in AS 200.
  B. R1 will load balance between three paths to reach the 192.168.1.48/28 prefix because all three paths have the same advertised distance (AD) of 40512000.
  C. The best path for R1 to reach the 192.168.1.48/28 prefix is via 192.168.1.66.
  D. 40512000 is the advertised distance (AD) via 192.168.1.66 to reach the 192.168.1.48/28 prefix.
  E. All the routes are in the passive mode because these routes are in the hold-down state.
  F. All the routes are in the passive mode because R1 is in the query process for those routes.
  A. R1 is in AS 200.
  C. The best path for R1 to reach the 192.168.1.48/28 prefix is via 192.168.1.66.
  D. 40512000 is the advertised distance (AD) via 192.168.1.66 to reach the 192.168.1.48/28 prefix.

  ---

  It can be determined that AS 200 is used, from the fact that the IS-IS process ID is labeled as 200. The best path to reach the network 192.168.1.48/28 is the first one displayed in the routing table. This can be further demonstrated by the fact that the metric is less than the alternative route, via serial 0. Finally, the AD can be found by viewing the second number within the parentheses, which in this case is 40512000.