Cisco CCNP Enterprise 300-410 Questions & Answers

• Question 151:

  When an EIGRP router starts, it sends a hello packet out of all interfaces.

  Which type of packet do neighboring routers send in response?

  A. ACK

  B. Hello

  C. Query

  D. Reply

  E. Update

  Correct Answer: E

  When an EIGRP router starts, it sends hello packets out of each interface. Neighboring routers respond with update packets. These update packets are sent reliably, and must be acknowledged with an ACK packet from the EIGRP router.

  EIGRP makes neighbor relationships simple. If a router hears a hello from a new neighbor, it sends that neighbor updates for all routes that it knows. This is different from Open Shortest Path First (OSPF), which has a complex series of rules

  governing how neighbor relationships are formed and how databases are synchronized. When changes to the network occur in OSPF, updates packets route reliable change information only to the affected routes.

  Queries and replies in EIGRP only occur when a router loses a route to a network and is actively seeking a replacement route.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Describe EIGRP packet types

  References:

  Internetworking Technology Handbook > Enhanced Interior Gateway Routing Protocol (EIGRP) > EIGRP Packet Types

• Question 152:

  What does the passive-interface command do when implement with RIP? (Choose two.)

  A. Allows an interface to receive routing update traffic

  B. Prevents an interface from sending routing update traffic

  C. Prevents an interface from sending any normal data traffic

  D. Allows an interface to receive normal data traffic

  E. Disables a router interface

  F. Places a router interface in standby mode

  Correct Answer: AB

  The effect of the passive-interface command is dependent on the routing protocol running on the interface. For EIGRP, the router will not only stop sending routing updates, but also hellos, which means that it will not form a neighbor relationship with another EIGRP router on that interface. This is also the case with OSPF and IS-IS. With RIP, however, the router will continue to send hellos even as it stops sending routing updates, and it will still receive routing updates. An example of using the passive-interface command is below. The command is issued from the router configuration mode.

  Router(config-router)# passive-interface ethernet 0/0

  The passive-interface command will even overrule a configuration that includes a distribute list that allows the advertisement of a network through the interface. Examine the partial output of the show run command taken from a router running EIGRP below: router6#show run ! router eigrp 100

  network 10.16.18.0 0.0.255.255

  network 10.16.19.0 0.0.255.255

  passive-interface serial 0/0

  distribute-list 50 out serial 0/0

  !

  Access-list 50 permit 10.16.8.0 0.0.255.255

  In this case, although the distribute list allows the advertisement of the 10.16.8.0 network, the passive- interface command applied to the Serial 0/0 interface will disallow all outgoing and incoming updates.

  The passive-interface command does not affect the transmission or reception of normal data traffic, only routing updates.

  The passive-interface command does not disable the router interface. The shutdown command is used to disable a router interface.

  The passive-interface command does not place the router in standby mode.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify loop prevention mechanisms

  References:

  Cisco > Home > Support > Technology Support > IP > IP Routing > Design > Design Technotes > How Does the Passive Interface Feature Work in EIGRP? Cisco > Cisco IOS IP Routing: Protocol-Independent Configuration Guide, Release

  12.4 > Configuring IP Routing Protocol-Independent Features > Filtering Routing Information Cisco > Cisco IOS IP Routing: Protocol-Independent Command Reference > passive-interface

• Question 153:

  As the network administrator, you need to develop a verification plan for an OSPF network. The OSPF network has several area routers, area border routers (ABRs), and autonomous system boundary routers (ASBRs).

  Which LSA types should you expect ABRs to generate while verifying the OSPF network? (Choose two.)

  A. Type 4

  B. Type 3

  C. Type 2

  D. Type 5

  Correct Answer: AB

  ABRs generate Type 3 and Type 4 LSAs in an OSPF network. ABRs are those routers that exist between two OSPF areas, as shown in the following figure:

  

  Type 3 and Type 4 LSAs are generated by ABRs to be flooded into other areas to and from the backbone area (area 0). Type 3 LSAs, or summary link advertisements, contain the list of networks known by one area. ABRs send Type 3 LSAs

  to the other OSPF areas in a given AS.

  OSPF ABRs generates Type 4 LSAs to advertise the list of routes that point to an ASBR. These LSAs advertise the location of the ASBR.

  Type 5 LSAs are not generated by an ABR. These LSAs are generated by ASBRs to describe routes redistributed into the area from other autonomous systems.

  Type 2 LSAs are not generated by an ABR. A Type 2 LSA is generated only by the designated router (DR) of a segment to be sent to the other routers that belong to the same area as the DR. A DR is a router that has the highest OSPF

  priority on a segment. These advertisements are used by the DR to represent the routers that are connected to the network.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify network types, area types, and router types

  References:

  Cisco Learning Home > Groups > CCNP RandS Study Group > Discussions > OSPF Level of Detail Cisco > Support > Technology Support > IP > IP Routing > Technology Information > Technology White Paper > OSPF Design Guide > Link

  State Packets

• Question 154:

  Examine the exhibit.

  

  You have determined that RTR2 is not advertising the CIDR summary address 192.168.0.0 to the other routers in AS 65100.

  Which set of configuration commands will enable the BGP router RTR2 to announce the network prefix 192.168.0.0/16 to the other routers in the AS 65100?

  A. router bgp 65100 neighbor 172.16.1.2 remote-as 65100 neighbor 192.168.3.2 remote-as 65100 network 192.168.3.0

  B. router bgp 65100 neighbor 172.16.1.2 remote-as 65101 neighbor 192.168.3.2 remote-as 65100 network 192.168.0.0

  C. router bgp 65100 neighbor 172.16.1.2 remote-as 65100 neighbor 192.168.3.2 remote-as 65100 network 192.168.0.0 mask 255.255.0.0 ip route 192.0.0.0 255.0.0.0 null 0

  D. router bgp 65100 neighbor 172.16.1.2 remote-as 65101 neighbor 192.168.3.2 remote-as 65100 network 192.168.0.0 mask 255.255.0.0 ip route 192.168.0.0 255.255.0.0 null 0

  Correct Answer: D

  Issuing the following commands will cause RTR2 to advertise the CIDR block 192.168.0.0/16 to the other routers by using BGP:

  RTR2(config)# router bgp 65100

  RTR2(config-router)# neighbor 172.16.1.2 remote-as 65101

  RTR2(config-router)# neighbor 192.168.3.2 remote-as 65100

  RTR2(config-router)# network 192.168.0.0 mask 255.255.0.0

  RTR2(config-router)# ip route 192.168.0.0 255.255.0.0 null 0 The network command specifies the address that will be inserted into the BGP table. Without the mask keyword, the classful network will be assumed. Because 255.255.0.0, or /16,

  is not the natural mask for any Class C address, the mask keyword must also be specified. Thus, 192.168.0.0 and 255.255.0.0 identify the desired address and mask of the 192.168.0.0/16 network prefix.

  The router checks the IP forwarding table for an exact match before it advertises the route. Without a matching entry in the IP forwarding table, that route will not be advertised. RTR2 must be able to advertise a CIDR block and not the

  individual subnets. A static route is required because BGP requires that a match of the network prefix be present in the forwarding table when using the network command with the mask keyword. Therefore, to ensure an exact match for the

  identified prefix exists in the IP forwarding table, and to ensure that the prefix will always be advertised, a static route for 192.168.0.0/16 to null 0 is also required.

  The syntax for the network command is shown below:

  network network-number [ mask network-mask ] [ route-map map-tag ]

  The parameters are:

  mask - This parameter is optional and identifies the network or subnetwork to advertise. route-map - This parameter is optional and identifies a preconfigured route-map that will be used to filter specific addresses from being advertised.

  The following command set is missing the mask keyword in the network command and the command to create a static route to null 0. The address used in the network command is also incorrect. It should 192.168.0.0:

  router bgp 65100

  neighbor 172.16.1.2 remote-as 65100

  neighbor 192.168.3.2 remote-as 65100

  network 192.168.3.0

  The following command set is missing the mask keyword in the network command and the command to create a static route to null 0:

  router bgp 65100

  neighbor 172.16.1.2 remote-as 65101

  neighbor 192.168.3.2 remote-as 65100

  network 192.168.0.0

  The following command set uses an incorrect mask (255.0.0.0) in the command that creates the static route to null 0. It should be 255.255.0.0:

  router bgp 65100

  neighbor 172.16.1.2 remote-as 65100

  neighbor 192.168.3.2 remote-as 65100

  network 192.168.0.0 mask 255.255.0.0

  ip route 192.0.0.0 255.0.0.0 null 0

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Describe, configure, and verify BGP peer relationships and authentication

  References:

  Internetworking Case Studies > Using the Border Gateway Protocol for Interdomain Routing > Controlling the Flow of BGP Updates > CIDR and Aggregate Addresses > Aggregation and Static Routes

• Question 155:

  Examine the following output.

  

  You are investigating why router RouterA does not include the 172.16.0.0 network in its BGP advertisements. The output contains portions of RouterA's configuration and IP routing table.

  Which statement correctly identifies the reason why this subnet does not appear in the BGP advertisements?

  A. BGP synchronization is enabled by default.

  B. The no auto-summary command was used.

  C. The 172.16.31.0/24 network was learned through BGP.

  D. The 10.1.2.3 IP address was not defined as a BGP neighbor.

  Correct Answer: B

  The no auto-summary command affects how a network identified by using the network command is advertised. The way the router in the exhibit is configured, it will not announce the 172.16.31.0/24 subnet. The BGP router will announce the

  classful address 172.16.0.0/16 when the routing table, maintained by the IGP, contains an exact match to the network command.

  The network command directly affects what network is advertised in BGP. If the command does not also include a network mask, and if auto-summary is enabled, then the classful address 172.16.0.0 is advertised any time that the router

  learns about a subnet of 172.16.0.0 via its IGP such as OSPF or EIGRP. The routing table does contain an entry for the 172.16.31.0/24 subnet that was learned through the IGP. However, auto- summary is disabled with the no auto-summary

  command. Therefore, only networks in the routing table that are an exact match to the network commands are advertised.

  If the configuration goal is to announce the 172.16.0.0/16 network any time one of its subnets is learned, such as 172.16.31.0/24, then you should enable auto-summary. If the goal is to announce only the 172.16.31.0/24 subnet learned

  through the IGP, then you should alter the network command's IP address and include the subnet mask.

  The BGP synchronization rule specifies that networks will not be advertised or used via iBGP unless it also has been learned through an IGP. If synchronization is disabled, iGBP will advertise a network without also learning it through an IGP.

  It does not affect the summarization of routes.

  The 172.16.31.0 network was learned through an IGP session with router 10.1.2.3.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify eBGP (IPv4 and IPv6 address families)

  References:

  Cisco IOS Master Command List, Release 12.4 > a through b > BGP Commands: A through B > auto- summary (BGP)

  Cisco > Cisco IOS IP Routing: BGP Command Reference > router bgp Cisco > Cisco IOS IP Routing: BGP Command Reference > network (BGP and multiprotocol BGP)

• Question 156:

  Which method should you use to block all routing updates from being sent into a network through an interface?

  A. Static route

  B. Default route

  C. Passive interface

  D. Route-update filtering

  Correct Answer: C

  To stop all outbound routing updates from an interface, you can use the passive-interface command. The effect of the passive-interface command is dependent on the routing protocol running on the interface. For EIGRP, the router will not

  only stop sending routing updates, but also hellos, which means that it will not form a neighbor relationship with another EIGRP router on that interface. This is also the case with OSPF and IS-IS. With RIP, however, the router will continue to

  send hellos even as it stops sending routing updates and it will still receive routing updates.

  There are numerous reasons to use the passive-interface command. For instance, suppose that you have a LAN with only end hosts on it and no other router. Additionally, there is no reason to send EIGRP packets, but you want EIGRP to

  advertise that the network can be reached. The combination of a network statement for that interface plus a passive-interface command would be appropriate.

  Route-update filtering can block all routing updates if you prefer, but it is really intended for selective filtering of updates. If your goal is to block all updates, the passive-interface command is best.

  Default routes and static routes can be used as ways around having to send routing updates out an interface. However, if your goal is to block updates, you should issue the passive-interface command.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Troubleshoot passive interfaces

  References:

  Cisco > Cisco IOS IP Routing: Protocol-Independent Command Reference > passive-interface Cisco > Home > Support > Technology Support > IP > IP Routing > Design > Design Technotes > How Does the Passive Interface Feature Work

  in EIGRP?

• Question 157:

  Which show command displays detailed information about a router's BGP connections to neighboring routers?

  A. show ip bgp

  B. show ip bgp summary

  C. show ip bgp neighbors

  D. show ip bgp connections

  Correct Answer: C

  The show ip bgp neighbors command will show you detailed information about all of the router's neighbors or peers. A sample of the show ip bgp neighbors output is shown below. The sample utilizes the ip address parameter, which is optional, but can used to limit the output to display information about only one neighbor:

  

  In the above example, router15 has sent out a BGP open packet to the peer at 10.5.1.6 and is listening for a connection request from the peer. This can be determined by the line that says BGP state = Active. It can also be determined that

  router has established a TCP connection two times, as evidenced by the line Connections established 2.

  The show ip bgp command displays the contents of the BGP routing table. It will not display detailed information about a router's BGP connections to neighboring routers.

  The show ip bgp summary command displays a summary of the status of BGP connections. It will not display detailed information about a router's BGP connections to neighboring routers.

  There is no show ip bgp connections command.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Describe, configure, and verify BGP peer relationships and authentication

  References:

  Cisco IOS Master Command List, Release 12.4 > a through b > BGP Commands: show ip through T > show ip bgp neighbors

• Question 158:

  You have configured OSPF on your network and enabled route summarization on an area border router (ABR) with the following command:

  Router(config-router)# area 3 range 165.164.8.0 255.255.248.0

  What does the 3 specify in this command?

  A. The ID of the OSPF backbone

  B. The number of networks summarized in the area

  C. The ID of the area about which routes will be summarized

  D. The ID of the area to which the summary route information will be sent

  Correct Answer: C

  The 3 in the area range command specifies the area that contains the routes that are to be summarized. In OSPF, you can only configure summarization on the border routers. The summaries need to be of routes within a single area. You summarize the routes of an area so that routers in another area do not see the individual networks, just the summary. The correct command syntax is shown below:

  area number range ip-address mask

  The number parameter is the number of the area whose networks are being summarized. For example, in the network shown in the graphic below, to summarize the networks within area 2 to 10.1.0.0/16, you would configure router A with the command area 2 range 10.1.0.0 255.255.0.0. This would not affect the routing tables of the routers within area 2, but instead make the routing tables of areas 0 and 1 smaller. These other routers would only have the summary route listed instead of the individual networks. Router C would only see the summary route 10.1.0.0/16.

  

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify manual and autosummarization with any routing protocol References:

  Cisco IOS Master Command Reference > a through b > area range

• Question 159:

  Which of the following commands is used to verify the link-local, global unicast, and multicast addresses of an IPv6 router?

  A. show ipv6 neighbors (only link-local addresses)

  B. show ipv6 route

  C. show ipv6 protocols

  D. show ipv6 interface

  Correct Answer: D

  The show ipv6 interface command is used to verify the link-local, global unicast, and multicast addresses assigned to an IPv6-enabled router interface. The show ipv6 interface command displays information regarding that interface, such as the physical state, MTU, and IPv6 enable/disable state.

  A partial output of the show ipv6 interface command on an IPv6-enabled router named rtrA is as follows:

  

  In the given sample output, you can see that the Fa0/1 interface of rtrA has the link-local address FE80::6339:7BFF:FE5D:A031/64 and the global unicast address 2001:7067:90D1:1::1. The global unicast address is not in EUI-64 format because when the ipv6 address command was issued, the eui64 keyword was not used. If EUI-64 format had been specified with the eui64 keyword, the global unicast address would have been 2001:7067:90D1:1:6339:7BFF:FE5D:A031.

  An IPv6-enabled interface has not only a link-local and global unicast address, but also one or more multicast addresses. A multicast address is an IPv6 address that has the prefix FF00::/8. These addresses are assigned to interfaces of different nodes such that they appear as a logical group. This implies that when a packet is destined for a multicast address, that packet is delivered to all the interfaces that have the same multicast address. The various multicast groups are as follows: FF02::1 Indicates the group of all the nodes on the local segment FF02::2 Indicates the group of all the routers on the local segment FF02::1:FF00:0/104 Indicates a solicited-node multicast group for every unicast or anycast address assigned to the interface

  You can also notice in the sample output that the Fa0/1 interface belongs to three multicast groups: FF02::1, FF02::2, and FF02::1:FF5D:A031. The first two multicast groups refer to the all-host and all-router multicast groups, respectively. The third group, FF02::1:FF5D:A031, is the solicited-node multicast address. This address is created for every unicast or anycast address. A solicited-node multicast address is determined by assigning the least significant 24 bits of the

  unicast address to the least significant 24 bits of the FF02::1:FF00:0 address.

  The show ipv6 neighbors command displays the link-local /global unicast addresses of the neighbors, including other information such as state and the next-hop interface.

  The show ipv6 route command is used to view the IPv6 routing table on the router. This command displays the prefixes, administrative distance, metric, and next-hop addresses for various IPv6 networks.

  The show ipv6 protocols command is used to view the active routing protocols for IPv6 on the router. This command shows the interfaces, redistribution status, and summarization status about each of the routing protocols enabled on the

  router.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Identify IPv6 addressing and subnetting

  References:

  Cisco IOS IPv6 Command Reference > show ipv6 eigrp topology through show ipv6 nat statistics > show ipv6 interface

  Cisco IOS IPv6 Command Reference > show ipv6 nat translations through show ipv6 protocols > show ipv6 neighbors

  Cisco IOS IPv6 Command Reference > show ipv6 nat translations through show ipv6 protocols > show ipv6 protocols

  Cisco > Products and Services > Cisco IOS and NX-OS Software > Cisco IOS Technologies > IPv6 > Product Literature > White Papers > Cisco IOS IPv6 Multicast Introduction Cisco > IPv6 Implementation Guide, Release 15.2MandT >

  Implementing IPv6 Multicast

• Question 160:

  You executed the following commands to assign an IPv6 link-local address to the Fa0/0 interface of the R1 router:

  R1(config)# interface Fa0/0 R1(config-if)# ipv6 ospf 1 area 1

  When you executed the show running-config command on the R1 router, you observed that OSPF for IPv6 is not running on the router.

  Which of the following commands should be added to the interface configuration?

  A. ipv6 router ospf

  B. ipv6 enable

  C. ipv6 ospf neighbor

  D. ipv6 ospf cost

  Correct Answer: B

  The ipv6 enable command should be used on R1 to enable IPv6. This command automatically provides an IPv6 link-local unicast address for the interface on which IPv6 is being configured. If an explicit IPv6 address were configured on the

  interface, the command would not be required.

  The ipv6 router ospf command should not be used in the configuration because this command allows you to enter the router configuration mode for OSPF for IPv6.

  The ipv6 ospf neighbor command is used to configure neighboring routers for OSPF. The ipv6 ospf cost command should not be added to the configuration because this command allows you to specify the OSPF cost to send packets from a

  given interface.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify OSPF for IPv6

  References:

  Cisco > Cisco IOS IPv6 Command Reference > ipv6 enable