CCNP Route Practice 2 Flashcards
Which of the following statements is NOT true about BGP peers?
A. eBGP peers use TCP to communicate
B. eBGP ppers use port 179 by default
C. eBGP peers do not update the AS_Path attribute before sending updates to another eBGP peer
D. iBGP peers do not update the AS_Path attribute before sending updates to an iBGP peer.
Answer: C Explanation:
External BGP (eBGP) peers do update the AS_Path attribute before sending updates to another eBGP peer. This helps to maintain the path back to the source of the update.
eBGP peers use TCP to communicate, and they do so on port 179 by default.
Internal BGP (BGP) peers are routers that reside in the same AS. iBGP peers do not update the AS_Path attribute before sending updates to an iBGP peer. That is only done when an update is sent from an eBGP peer to another eBGP peer.
Objective:
Layer 3 Technologies
Sub-Objective:
Explain BGP attributes and best-path selection
References:
Home > About Cisco > Publications and Merchandise > The Internet Protocol Journal > Back issues > Volume 9,Number 1, March 2006 > Autonomous System Numbers > Exploring Autonomous System Numbers
Which of the following IPv4 migrations techniques does not separate DNS and the translations process
A. NAT-PT
B. stateless NAT64
C. stateful NAT64
D. MAP-T
Answer: A
Explanation:
Network Address Translation-Protocol Translation (NAT-PT) and DNS are inseparable, which is one of the reasons why NAT-PT has been deprecated. Network Address Translation IPv6 to IPv4, or NAT64, is superior to the NAT-PT technique because this solution has complete separation of the functions of NAT64 and DNS64.
Stateless NAT64 is a version of NAT64 that does not maintain a binding or session state when it performs Address Family Translation (AFT). As such, it cannot be used in some of the implementations in which stateful NAT 64 can. However, in this method, DNS and the translation process are independent.
Stateful NAT64 creates or modifies bindings or session state while performing translation. For this reason, it can be used to translate from an IPv4 network to an IPv6 network if static mappings are created, which stateless NAT64 cannot.
Mapping of Address and Ports using Translation (MAP-T) is a method of creating mappings to provide connectivity for IPv4 hosts across an IPv6 domain. Its operation is not connected to DNS.
Objective:
Infrastructure Services Sub-Objective:
Describe IPv6 NAT
Router R2 has been configured with the following OSPF router command: area 1 range 130.31.96.0 255.255.224.0
Which address listed will be summarized by R2 into area 0? (chose all that apply)
A. 130.31.128.0/23
B. 130.31.112.0/20
C. 130.31.130.0/24
D. 130.31.160.0/22
E. 130.31.104.0/21
Answer: B, E
Explanation:
The command area 1 range130.31.96.0 255.255.224.0 is used to summarize the IP network addresses from 130.31.96.0/24 to 130.31.127.0/24 in area 1. Addresses 130.31.112.0/20 and 130.31.104.0/21 are both in that range of network addresses.
To determine if an address is a part of a summary, put the summary address and summary mask in binary format. Do the same with the address and the summary mask you are examining, as shown below:
- 31.96.0 10000010.00001111.01100000.00000000
- 31.112.0 10000010.00001111.01110000.00000000
- 255.224.0 11111111.11111111.11100000.00000000
If the address you are testing and the summary address agree to the point where the mask stops, then the test address is part of the summary. In this case, they agree through the 27th bit, so this address is a part of the summary. The same is true for the 130.31.104.0 address.
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 is:
area area id range ip-address mask
The area id parameter is the number of the area whose networks are being summarized. For example, in the network shown in the exhibit, to summarize the networks within area 1 to 130.31.96.0/19 you would configure router R2 with the command area 1 range 130.31.96.0 255.255.224.0. This would not affect the routing tables of the routers within area 1, but instead make the routing tables of areas 0 and 2 smaller. These other routers would only have the summary route listed instead of the individual networks. Router 3 would only see the summary route 130.31.96.0/19.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify manual and autosummarization with any routing protocol
References:
Cisco > Home > Support > Technology Support > IP Routing > Technology Information > Technology White Paper > OSPF Design Guide > OSPF and Route Summarization > Inter-Area Route Summarization
Cisco IOS Master Command List, Release 12.4 > a through b > area range
You are implementing IP SLA and would like to use it to measure hop-by-hop response time between a Cisco rotuer and any IP device on the network.
Which of the following IP SLA operations would you use for this?
A. ICMP path echo operation
B. Internet Control Message Protocol Echo Operation
C. UDP Jitter Operation for VoIP
D. UDP Jitter Operation
Answer: A
Explanation:
The ICMP path echo operation discovers the path using the traceroute command, and then measures response time between the source router and each intermittent hop in the path. IP SLAs allow users to monitor network performance between Cisco routers or from either a Cisco router to a remote IP device.
The Internet Control Message Protocol (ICMP) Echo Operation measures end-to-end response time between a Cisco router and any IP-enabled device. Response time is computed by measuring the time taken between sending an ICMP echo request message to the destination and receiving an ICMP echo reply. It does not measure hop-by-hop response time.
The UDP Jitter Operation for VoIP is an extension to the current jitter operations with specific enhancements for VoIP. The enhancements allow this operation to calculate voice quality scores and simulate the codec’s directly in CLI and the MIB. It does not measure hop-by-hop response time.
The UDP Jitter Operation is designed to measure the delay, delay variance, and packet loss in IP networks by generating active UDP traffic. It does not measure hop-by-hop response time.
Objective:
Infrastructure Services
Sub-Objective:
Describe SLA architecture
References:
Home > Support > Technology support > IP > IP application services > Technology information > Technology white paper > Cisco IOS IP Service Level Agreements User Guide
Which command is the proper command for allowing RIP routing updates to be received on an interface while not allowing them to be sent out of the same interface.
A. Router(config)#passive-interface e0/0
B. Router(config)#passive-interface
C. Router(config-if)#interface passive
D. Router(config-router)#passive-interface e0/0
E. Router(config-router)#interface passive e0/0
Answer: D
Explanation:
The correct answer is as follows:
Router(config-router)# passive-interface e010
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.
The passive-interface command issued at the router configuration mode will prevent routing updates from being sent out on a specific interface while still allowing the interface to receive updates. This command can be used in any situation where you want the router to receive routing updates on a particular interface but not send any updates. This is helpful for security purposes, for preventing routing loops, or to control routing update traffic.
The other options either use improper syntax or are executed at an incorrect prompt.
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 Command Reference > passive-interface
Which of the following commands should you use to determine both the feasible successors and the non-feasible successors to a given destination network?
destination network?
A show ip route eigrp
B show ip eigrp topology
C show ip eigrp topology all-links
D show ip eigrp topology zero-successors
Answer: C Explanation:
The show ip eigrp topology all-links command displays both feasible successors and non-feasible successors to a given destination network. This command displays the contents of the topology table and shows all the routes available for a given destination network.
An example of partial output of the command is below:
R2# show ip eigrp topology- all-links IP-EIGRP Topology Table for process 666
Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,
- Reply status
- 172.17.1.0/24, 1 successors, FD is 2169856 via Connected, Serial()
- 172.16.1.0/24, 1 successors, FD is 2195456 via 172.17.1.1 (2195456/281600), Serial()
- 172.19.1.0/24, 1 successors, FD is 2297856, tag is 1 via 172.17.1.1 (2297856/128256), Serial()
- 172.20.2.0/24, 1 successor, FD is 2469831
- Via 172.17.3.1 (2469831/2413698), Serial1
- Via 172.17.1.1 (2475369/2443698), Serial0
- 172.25.1.0/24, 1 successor, FD is 2496831
- Via 172.17.3.1 (2496831/2413468), Serial1
- Via 172.17.1.1 (2596481/2501649), Serial0
The 172.20.2.0/24 network has a feasible successor. This can be determined by looking at the values in the parenthesis next to each route. The second value after the / is the advertised distance from the successor. This value must be less than the value of the feasible distance for a route to be considered a feasible successor. There are two routes for 1722020/24. The first route listed, via 172.17.3.1, is the successor route. Its cost is 246983122, which matches the feasible distance (FD). The second route, via 172.17.1.1, has an advertised distance of 2443698 (the second value in the parentheses after the /). Because this value is less than the FD (2413698), it qualifies as a feasible successor.
The 172.25.1.0/24 network does not have a feasible successor. The second route listed via 172.17.1.1 has an advertised distance of 2501649, which is greater than the value of the FD, (2416381). Therefore, it is not a feasible successor.
You should not use the show ip route eigrp command. This command displays only the best metric routes (successors) to a given destination network. A route has the best metric if it has the least feasible distance, which refers to the sum of the metric from a given neighbor to a destination network and the metric to reach that neighbor.
You should not use the show ip eigrp topology command without the all-links parameter. This command displays only the feasible successors to a given destination network.
You should not use the show ip eigrp topology zero-successors command because this command lists those routes that do not have a valid successor.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify policy-based routing
References:
Cisco IOS IP Routing: EIGRP Command Reference > show ip eigrp topology
Which EIGRP packet type is sent as a mufticast when a new route is discovered, and sent as a unicast to synchronize topology tables when
neighbors initialize?
A ACK
B Hello
C Update
D Replies
E Queries
Answer: C
Explanation:
EIGRP update packets are sent as a mutticast when a new route is discovered, and sent as a unicast to synchronize topology tables when a neighboring router initializes.
Whenever EIGRP only needs to communicate with a single neighbor, it sends a unicast to that neighbor instead of the standard mutticast. In this case, it unicasts a packet to update a new EIGRP router on the network with the information that all other routers on that network already know.
Hellos for neighbor discovery and maintenance are always mutticasts. ACKs are hellos without data, and are always unicast.
Queries are always mutticast.
Replies to queries are always unicast.
Objective:
Layer 3 Technologies
Sub-Objective:
Describe EIGRP packet types
References:
Internetworking Technology Handbook > Enhanced Interior Gateway Routing Protocol (EIGRP) > EIGRP Packet Types
Which of the following actions will make area 1 a totally stubby area? (Choose all that apply. Each correct answer is part of the solution.)
A execute the area 1 stub no-summary command on RouterA
B execute the area 1 stub no-summary command on RouterB
C execute the area 1 stub command on RouterB
D execute the area 1 stub command on RouterA
E execute the area 0 stub-no summary command on RouterA
F execute the area 0 stub no-summary command on RouterB
G execute the area 0 stub command on RouterB
H execute the area 0 stub command on RouterA
Answer: A, C
Explanation:
You should execute the area 1 stub no-summary command on RouterA and the area 1 stub command on RouterB. A totally stubby area is one that only keeps local area routes in the link-state database (LSDB), plus a default route that leads out of the area. To make an area totally stubby, the area border router (ABR) should be configured with the area 1 stub no-summary command and all other area routers should be configured with the area 1 stub command. The diagram in the scenario indicates that RouterA is the border router.
You should not run any of the commands that refer to area 0. This would affect a different area than the requirement stated in the scenario. None of the other combinations of actions will create a totally stubby area.
If you run the area 1 stub command on both RouterA and RouterB, it will create a stub area. A stub area differs from a totally stubby area in that a stub area will allow updates about areas in the same OSPF domain.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify network types, area types, and router types
References:
Cisco > Home > Support > Technology Support > IP > IP Routing > Design > Design Technotes > What Are OSPF Areas and Virtual Links? > Define a Totally Stub Area
What is the next-hop address when rtrB advertises the 2001:5050:D402:B333:164 IPv6 subnet to rtrC?
A. FE80::3030:3030:3030/64
B. FE80::3230:3030:3030/64
C. FE80::3030:30FF:FE30:3030164
D. FE80::3230:30FF:FE30:3030/64
Answer: D
Explanation:
The next-hop address when rtrB advertises the 2001:5050:D402:B333:164 IPv6 subnet to rtrC is FE80::3230:30FF:FE30:3030/64. In routers with EIGRP for IPv6 enabled on them, the next-hop address is the IP address of the interface that advertises routes. The next-hop addresses should be link-local addresses. Link-local addresses are IPv6 unicast addresses that are automatically assigned to the router interfaces. These addresses have the FE80:110 prefix and the EUI-64 standard interface address.
EUI-64 is an IEEE standard that allows the determination of an IPv6 address from the MAC address of an interface. The 64 most significant bits should be specified in the ipv6 address command. The 64 least significant bits are determined by using the EUI-64 standard. The steps to determine the 64 least significant bits are as follows:
- Divide the 48-bit MAC address into two 24-bit parts.
- Embed FFFE (16 bits) between the two parts resulting in a 64-bit address.
- If required, toggle the seventh bit of the first octet in the address. In EUI-64 format, if the seventh bit is 0, then the address is local. If the seventh bit is 1, the address is global.
In this case, when rtrB advertises any route to rtrC, it advertises the interface with the MAC address 3030.3030.3030 as the next-hop. When the given steps are performed on the MAC address, it result in the EUI-64 standard address 3230.30FF.FE30:3030. This address is then appended to the FE80:110 prefix. The resultant IPv6 link-local address of the interface is FE80::3230.30FF.FE30:3030/10.
The remaining three options are incorrect as their interface address is not in the EUI-64 standard.
Objective:
Layer 3 Technologies
Sub-Objective:
Identify IPv6 addressing and subnetting
References:
Cisco IPv6 Configuration Guide, Release 15.2 > IPv6 Neighbor Redirect Message
Cisco IPv6 Configuration Guide, Release 15.2 > IPv6 Unicast Routing > Aggregatable Global Address
You have enabled RIPng on one of the interfaces of a router with the basic configuration. You have assigned an address to that interface
using the ipv6 address command.
Which of the following statements should appear in the output of the show running-config command executed on the router? (Choose all that
apply.)
A ipv6 unicast-routing
B ipv6 enable
C ipv6 rip enable
D ipv6 router rip
E ipv6 unnumbered
F ipv6 prefix-list
Answer: A, C
Explanation:
The ipv6 unicast-routing and ipv6 rip enable statements should appear in the output of the show running-config command.
The ipv6 unicast-routing command is one of the basic IPv6 commands that needs to be executed on any router for IPv6 processing. This command is executed in the global configuration mode to allow IPv6 packet forwarding on the router. When it has been executed the ipv6 unicast-routing statement will appear in the output of the show run command.
The ipv6 rip enable command allows you to enable RIPng on a router interface. You should execute this command to create a RIPng routing process.
When it has been executed the ipv6 rip enable statement will appear in the output of the show run command.
The ipv6 router rip command allows you to work with RIPng routing process by entering the router configuration mode for RIPng. It will only appear if modifications have been made to the RIPng routing process, which is not mentioned in this case.
The commands to configure a router with RIPng is as follows:
rtrA(config)# ipv6 unicast-routing
rtrA(config)# interface Fa0/1
rtrA(config-if)# ipv6 rip rip process enable rtrA(config-if)# ipv6 address 2001:1:1:1::1/64
Important note: in the command set above, the command that enables the RIP process on interface Fa0/1 is executed before the command assigning the IPv6 address. The order of execution of those two commands does not matter. However, if a configuration file is copied and pasted into a router, then the order in which the statements appear does matter.
For example, if the partial configuration below were pasted into a router, the IPv6 RIP process 56 would not be enabled on Fa0/0:
ip unicast routing
interface Fa0/0
ipv6 rip 56 enable
ipv6 address 2001:1:1:1::1164
The system would reject the ipv6 rip 56 enable command because an IPv6 address is not yet present. If the commands were reversed in the file, the system would accept the ipv6 rip 56 enable command.
In the scenario, the ipv6 enable command does not appear in the show running-config output. This command enables IPv6 routing on a router interface that has not been assigned an IPv6 address. In this case, an IPv6 address is explicitly assigned to the router interface by using the ipv6 address command. Therefore, the ipv6 enable command is not required.
The ipv6 unnumbered interface type command does not appear in the show running-config output. This command will allow you to enable IPv6 without assigning an IPv6 address to a router interface.
Objective:
Layer 3 Technologies Sub-Objective:
Describe RIPng
References:
Cisco IPv6 Implementation Guide, Release 15.2M&T > Implementing RIP for IPv6 > How to Implement RIP for IPv6 > Enabling the IPv6 RIP Process
Cisco IPv6 Implementation Guide, Release 15.2M&T > Implementing RIP for IPv6 > Configuration Examples for IPv6 RIP > Examples: IPv6 RIP
Configuration Cisco IOS IPv6 Command Reference > ipv6 ospf dead-interval through ipv6 split-horizon eigrp > ipv6 rip enable
Cisco IOS IPv6 Command Reference > ipv6 ospf dead-interval through ipv6 split-horizon eigrp > ipv6 router rip
Cisco > Cisco IOS IPv6 Command Reference > ipv6 prefix-list
Cisco IOS IPv6 Command Reference > ipv6 summary-address through mpls Idp router-id > ipv6 unnumbered
You can use a variety of commands to verify and troubleshoot the operation of route redistribution on your network.
Which command should you NOT use on routers that are overloaded?
A. trace
B. debug
C. show ip route
D. show ipx route
Answer: B
Explanation:
The debug command uses a good deal of router CPU time, so you should not initiate this command on an already overloaded router. It often requires the router to do extensive examination of the packets, requiring heavy use of resources at times.
You could also possibly overload the router just with the debug command. If the router is overloaded to the point that it is no longer responding to your EXEC session, you may need to reload the router to stop the debug output.
These additional steps can help to verify proper route redistribution:
- On the router not performing the redistribution, use the show ip route command to see if the redistributed routes are displayed.
- On the router performing the redistribution, use the show ip protocol command to verify the redistribution configuration, and use the show ip route command that to verify the proper routes are there from each routing protocol.
The trace command is used to discover the route that packets take to their destination.
The show ip route command displays the routing table.
The show ip protocols command displays information about each routing protocol running on the router.
Objective:
Layer 3 Technologies Sub-Objective:
Configure and verify manual and autosummarization with any routing protocol References:
Cisco > Home > Support > Technology Support > Dial and Access > ISDN, CAS > Design > Design Technotes > Important Information on Debug Commands > Document ID: 10374
Cisco > Cisco IOS Debug Command Reference > Using Debug Commands
Examine the following output of the show ip route command and the partial output of the show run command from the router R63:
R63#shcw ip route
10.2.0.0/16 is variably subnetted, 2 subnets, 2 masks
C 10.2.1.0/24 is directly connected, Serial0/0
L 10.2.1.1/32 is directly connected, Serial0/0
10.0. 0.0/24 is 3ubnetted, 1 subnets
S 10.10.10.0 is directly connected, TunnelO
10.11.0. 0/24 is 3ubnetted, 1 subnets
S 10.11.11.0 is directly connected, Ethernet0/0
S 0.0.0.0/0 [1/0] via 172.21.114.65, EthernetO/1
R63#show run
<output></output>
interface Serial0/0
ip address 10.2.1.1 255.255.255.0
ip verify unicast source reachable via rx
What will the router do with a packet with a source address of 192.168.5.5/24 and a destination address of 10.11.11.20/ 24 that arrives on the Serial0/0 interface?
A. forward it out the Ethernet0/0 interface
B. forward it out the TunnelO interface
C. drop the packet
D. forward it out the Ethernet0/1 interface
Answer: C
Explanation:
It will drop the packet. The partial output of the show run command shows that the ip verify unicast source reachable via rx command has been executed on the Serial 0/0 interface. This enables the Unicast Reverse Path Forwarding (Unicast RPF) feature. This feature prevents IP spoofing by verifying from the routing table that there is a valid return path to the source IP address. If there is not valid return path, you can assume the IP address has been spoofed. When the command ends in the keyword rx, it means that there must be a return path through the interface where the command was executed. This is called strict mode.
The packet arrived on the SerialO/O interface. The routing table shows that there is no routing entry for the 192.168.5.0/24 network that leads back through the entry interface of SerialO/O. In fact, in this instance there is no routing table entry for that network leading to any interface. When this occurs, the router will drop the packet.
The router will not send the packet to either the Ethernet0/0 or the TunnelO interfaces because the destination network, 10.11.11.0/24, is not a reachable destination on those interfaces. Even if it were reachable, the Unicast Reverse Path Forwarding (Unicast RPF) feature will drop the packet because it has been spoofed.
It will not send the packet to the Ethernet0/1 interface. The Unicast Reverse Path Forwarding (Unicast RPF) feature will drop the packet because it has been spoofed. If the packet were not spoofed, it would be sent to the Ethernet0/1 interface because that is the interface used by the default route. Because there is no route in the table to the 10.11.11.0/24 network, it would be sent to the default route.
Objective:
Infrastructure Security Sub-Objective:
Configure and verify router security features References:
Cisco IOS Security Configuration Guide, Release 12.2 > Configuring Unicast Reverse Path Forwarding Cisco > Configuring Unicast Reverse Path Forwarding
Which commands will display the feasible successors, the feasible distance, and the advertised distance for networks learned by a router?
A. show ip eigrp topology
B. show ip route
C. show bgp neighbors
D. show ip eigrp traffic
E. show ip route eigrp
Answer: A
Explanation:
To view the feasible successors, the feasible distance, and the advertised distance, you would use the show ip eigrp topology command. A sample output of this command is below.
Router2# show ip eigrp topology IF-EIGRF Topology Table for process 100
Codes: F - Passive, A - Active, U - Update, Q - Query, R - Reply, r - Reply status
F 10.10.0.0/16, 1 successors, FD is 2169S56 via Connected, SerialO
SIA 10.0.0.0/8, 1 successors, FD is 2169856 via Summary (2169856/0), NullO F 10.20.0.0/16, 1 successors, FD is 2169856 via Connected, Seriall
F 65.0.0.0/8, 1 successors, FD is 2297856
via 10.20.0.1 (2297856/128256), Seriall
via 10.20.1.6 (2589799/2672569), FastEthernetO
F 192.163.10.0/24, 1 successors, FD is 2297856
via 10.10.0.1 (2297856/123256), SerialO
F 130.10.0.0/16, 1 successors, FD is 2297856
via 10.20.0.1 (2297856/123256), Seriall
F 150.10.0.0/16, 1 successors, FD is 2297856
via 10.10.0.1 (2297856/123256), SerialO
via 10.20.0.1 (2594536/2443152), FastEthernetl
F 200.10.10.0/24, 1 successors, FD is inaccessible, Q
2 replies, active never, query-origin, Successor Origin
via 10.1.1.3 (395212452/390742563), r, Serial 0
Remaining replies:
via 10.1.1.2, r, Serial 0
The table lists all routes to networks and their advertised distance and feasible distance. This information is used to select the successor and feasible successor for each network. Before a route can be considered as a feasible successor or backup, the feasible distance of the route must be a larger value than the advertised distance.
The following information can be extracted from this output:
- The route 15.10.0.0/16 has a feasible successor. If you examine the feasible and advertised distances in the brackets next to the two potential feasible successor routes [feasible distance/advertised distance], you will see that for the route 15.10.0.0/16 via 10.10.5.1, the feasible distance of the route is greater (2594586) than the advertised distance (2448152), which qualifies it as a feasible successor.
- The route 65.0.0.0/8 does not have a feasible successor. The route 65.0.0.0/8 via 10.20.1.6 has a feasible distance (2589779) that is less than the advertised distance (2672569), so it does not qualify.
The router at 10.20.0.1 is directly connected to the networks 65.0.0.0/8 and 150.10.0.0/16. This can be deduced by the fact that the address 10.20.0.1 is the source of the successor routes for those networks.
The route to 200.10.10.0/24 is undergoing recomputation, as evidenced by the line FD is Inaccessible. It also tells you that Router2 sent a query to 10.1.1.2 and is waiting for a reply, as evidenced by the line Remaining replies: via 10.1.1.2, r, Serial 0.
The route to the 10.0.0.0/8 network is showing a convergence problem, as evidenced by the code SIA to the left of its entry. This stands for Stuck In Active. An active state is present when the local router has queried for a new route to the network. Stuck in Active occurs when no response has been received, and the local router marks it SIA. The show ip route and the show ip route eigrp commands simply display the routing table, which does not display the advertised distance. Below is an example of the show ip route command executed on a router running EIGRP:
RouterA# show ip route Coutput omitted>
D 192.163.0.0/24 [90/21954636] via 172.16.10.44, 00:01:12, SerialO 172.16.0.0/16 is variably subr.etted, 7 subnets, 2 m.ask-3 D 172.16.10.96/29 [90/22794545] via 172.16.10.36, 00:05:09, Serial3 D 172.16.10.30/29 [90/21946536] via 172.16.10.74 00:05:12, Seriall D 172.16.10.38/29 [90/22746464] via 172.16.10.41, 00:13:50, Serial2 C 172.16.10.68/30 is directly connected, Seriall C 172.16.10.64/30 is directly connected, SerialO C 172.16.10.76/30 is directly connected, Serial3 C 172.16.10.72/30 is directly connected, Serial2
View the sample output of the debug ip eigrp command.
IP-EIGRP: Processing incoming REPLY packet
IP-EIGRP: Int 10.20.0.0/16 V. 4294967295 - 1657856 4294967295 SK 4294967295 - 1657856 4294967295 IP-EIGRP: Int 65.0.0.0/8 M 4294967295 - 1657856 4294967295 SK 4294967295 - 1657856 4294967295 IP-EIGRP: Int 130.10.0.0/16 H 4294967295 - 1657856 4294967295 SK 4294967295 - 1657856 4294967295
What is the significance of the number 4294967295 as shown in the output?
A. it represents the unreachable metric for EIGRP.
B. it represents the administrative distance for EIGRP.
C. it represents a reachable metric for the given network.
D. it represents one of the link characteristics that EIGRP uses to calculate the metric.
Answer: A
Explanation:
The value 4294967295 in the debug ip eigrp output represents the unreachable metric for EIGRP. This means that the network has become unavailable and cannot be reached. In this output, the M represents the local metric, and the SM represents the metric that was reported by the neighbor that advertised the network to the local router.
The administrative distance (AD) for internal EIGRP is 90.
The link characteristics that are used in the EIGRP calculation are shown following the dash after the M and SM values (1657856 4294967295). By default, EIGRP only uses bandwidth and delay in its calculation. Objective:
Layer 3 Technologies Sub-Objective:
Describe and optimize EIGRP metrics References:
Cisco > Cisco IOS Debug Command Reference > debug h225 asn1 through debug ip ftp > debug ip eigrp
You have been asked to troubleshoot the NTP configuration of a router named R70. After executing the show run command, you receive the following partial output of the command that shows the configuration relevant to
NTP:
clock timezone PST -8
clock summer-time PDT recurring
ntp update-calendar
ntp server 192.168.13.57
ntp server 192.168.11.58
interface Ethernet 0/0
ntp broadcast
Based on this output, which of the following statements is true?
A. the time zone is set to 8 hours less than Pacific Standard time
B. the router will listen for NTP broadcasts on interface E0/0
C. the router will send NTP broadcasts on interface E0/0
D. the router will periodically update its software clock
Answer: C
Explanation:
The router will send NTP broadcast on its E010 interface. The command ntp broadcast, when executed under an interface, instructs the router to send NTP broadcast packets on the interface. Any devices on the network that are set with the ntp broadcast client command on any interface will be listening for these NTP broadcasts. While the clients will not respond in any way, they will use the information in the NTP broadcast packets to synchronize their clocks with the information.
The time zone is not set to 8 hours less than Pacific Standard Time. The value -8 in the command clock timezone PST -8 is the amount of hours offset from UTC time, not from the time zone stated in the command.
The router will not listen for NTP broadcasts on the interface E0/0. The ntp broadcast command, when executed under an interface, instructs the router to send NTP broadcast packets on the interface. To set the interface to listen and use NTP broadcasts, you would execute the ntp broadcast client command on the interface.
The router will not periodically update its software clock. The command ntp update-calendar configures the system to update its hardware clock from the software clock at periodic intervals.
Objective:
Infrastructure Services
Sub-Objective:
Configure and verify Network Time Protocol (NTP)
References:
Basic System Management > Setting Time and Calendar Services > Configuring NTP
You instructed your associate to configure Router R2 to reject a redistribution of the 20.0.0.0/8 network,while still receiving routes from other networks connected to Router R1.The diagram below displays the network in place:
When he is finished,youfind that the 20.0.0.0/8 network still being advertised and traffic from the 20.0.0.0/8 network is not reaching Router2.You execute the show running-configuration command and see the following output:
Hostname Router 2
interface Seriall
ip address 10.0.0.2 255.0.0.0
ip access-group 101 in no ip redirects
router bgp 9688
network 10.0.0.0 mask 255.0.0.0.0
access-list 101 deny ip 20.0.0.0 0.255.255.255
access-list 101 permit ip any any
What is the problem?
A The access list was applied to the wrong interface.
B The access list should have beenconfigured as a distribute list.
C The access list has an incorrect wildcard mask.
D The access list is applied inthe wrong direction.
Answer: B
Explanation:
The access list should have been created as a distribute list to control route redistribution from the other area. This configuration would prevent the redistribution of the 20.0.0.0/8 network by applying the list as a distribute list under the Border Gateway Protocol (BGP). The proper commands would be:
Router2(config)# router bgp 94688
Router2(config-router)# distribute-list 101 in
To correct the problem with traffic not arriving from the 20.0.0.0/8 network, you must remove the application of the list under interface SO as well. This would be done by executing the following command set:
Router2(config)# interface Serial!
Router2(config-int)# no ip access-group 101 in
The access list was not applied to the wrong interface. It should not have been applied directly to any interface. When applied directly as an access list to an interface, it will prevent traffic, but not the redistribution of routes. The access list does not have an incorrect wildcard mask. To prevent the redistribution of a Class C network, the correct wildcard mask is 0.0.0.255.
The access list was not applied in the wrong direction. It should be applied incoming, but should be applied as an incoming distribute list, and it should be applied under the BGP protocol.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify littering with any protocol
References:
Cisco IOS Master Command List, Release 12.4T > d > distribute-list in (IP)
Cisco > Home > Support > Technology Support > IP > IP Routing > Design > Design Technotes > Filtering Routing Updates on Distance Vector IP Routing Protocols
You have two routers connected to each other that are both running the EIGRP protocol. The routers have built a neighbor relationship and are exchanging routing information. You execute the following command on the EIGRP process on Router 1:
routerl (config)# router eigrp 100
routerl (config-router)# passive-interface
What will be the effect of this command?
A. Only routing advertisements from Router 1 to Router 2 will be prevented.
B. Only router advertisements to and from Router 1 will be prevented.
C. All hellos and routing updates will be prevented, and the neighbor relationship between Router 1 and Router 2 will be broken
D. Hellos will be prevented, but routing updates will continue to be sent out.
Answer: C
Explanation:
The effect of the passive-interface command is dependent on the routing protocol. With RIP, the command prevents the sending of route updates, but does not prevent the reception of route updates. With EIGRP, the passive-interface command prevents both the sending and receiving of route updates, and also the sending of hellos. Without hello packets, the routers are unable to maintain the neighbor relationship, upon which all communications including route updates depend.
If the intent was to preventing routing updates from Router 1 to Router 2 while still allowing updates from Router 2 to Router 1, the routing updates must be filtered out and denied on Router 1 with a distribute list, as shown in the following command set:
router1(config)access-list 101 deny any
router1(config)#router eigrp 100
routerl (config-router)distribute-list 101 out
Objective:
Layer 3 Technologies
Sub-Objective:
Troubleshoot passive interfaces
References:
Cisco IOS Master Command List, Release 12.4T > p through r > passive-interface
Cisco > Home > Support > Technology Support > IP > IP Routing > Design > Design Technotes > Filtering Routing Updates on Distance Vector IP Routing Protocols
You configured a device as an IP SLA responder using the following configuration:
ip sla 9
tcp-connect 10.0.0.1 23 control disable
frequency 30 tos 128
timeout 1000 tag FLL-RO
ip sla schedule 9 start-time nsw
Which line indicates that the device is not a Cisco device?
A. frequency 30
B. timeout 1000
C. tcp-connect 10.0.0.1 23 control disable
D. tag FLL-RO
Answer: C
Explanation:
The IP SLA TCP connect operation is used to gather statistics on connection-oriented services. The tcp-connect 10.0.0.1 23 control disable command specifies the IP address to which the responder should respond, the port number on which to respond and it disables the control protocol normally used to inform the responder to temporarily enable the port specified by the configuration in the sender.
When the responder is a non-Cisco device, a well-known port number must be chosen and the control protocol should be disabled on the responder. When a Cisco device is the responder, then any port number can be chosen and the control protocol should be left enabled.
The frequency 30 command specifies how often the test should occur in seconds. It is not changed in any way as a result of the responder being a non-Cisco device.
The timeout 1000 command specifies in milliseconds the amount of time an IP SLAs operation waits for a response from its request packet. It is not changed in any way as a result of the responder being a non-Cisco device.
The tag FLL-RO command simply applies a user-specified identifier to the IP SLAs operation and is changed in any way as a result of the responder being a non-Cisco device.
Objective:
Infrastructure Services
Sub-Objective:
Configure and verify IP SLA
References:
IP SLAs Configuration Guide, Cisco IOS Release 15M&T > Configuring IP SLAs TCP Connect Operations Cisco > Cisco IOS IP SLAs Command Reference > tcp-connect
Which of the following IPv6 addresses correctly represent the shortened version of the IP address 2031:0000:0000:130F:0000:0000:876A:130B? (Choose two.)
A
2031::130F::876A:130B
B
2031::130F:0:0:876A:130B
C
2031:0:130F::876A:130B
D
2031:0:0:130F 876A:130B
Answer: B, D
Explanation:
2031:0000:0000:130F:0000:0000:876A:130B can be shortened to either 2031::130F:0:0:876A:130B or 2031:0:0:130F::876A:130B.
IPv6 addresses are written in 16-bit hexadecimal number fields separated by a colon (:). There are a total of eight 16-bit fields, making each IPv6 address a total of 128 bits. The hexadecimal letters are NOT case sensitive.
You can shorten an IPv6 address by removing the leading zeros in any address field. You can only remove zeros that are the first character in an address field. For example, FFC0:02C0: is the same as FFC0:2C0:. However, FFCO:8020 is not the same as FFC0:802:.
If a 16-bit address field contains all zeros, then it can be represented by a single zero. For example, FF80:0000: is the same as FF80:0:
You can use double colons (::) to represent successive address fields of zeros. An address parser can determine the number of missing fields and then insert the proper number of zeros to complete the address. For example, FF80:0000:0000:0000:0000:0000:0000:0001 is the same as FF80::1, and 0000:0000:0000:0000:0000:0000:0000:0001 could be written as ::1. However, you can only have one set of double colons (::) in an address; therefore, FF80:0000:0000:0CB0:0000:0000:0000:0001 cannot be written as F80::OCB0::1.
Objective:
Layer 3 Technologies
Sub-Objective:
Identify IPv6 addressing and subnetting
References:
Cisco > IPv6 Addressing and Basic Connectivity Configuration Guide > IPv6 Addressing and Basic Connectivity Cisco > IPv6 Addressing at a Glance (PDF)
The exhibit is a frame relay hub-and-spoke topology with router A as the hub.
You want to use the OSPF routing protocol between all three locations. Which interface configuration commands are required on router A? (Choose three.)
A. ip ospf network broadcast
B. ip ospf network point-to-point
C. ip ospf network point-to-multipoint
D. frame-relay map 10.20.10.21 221
E. frame-relay map 10.20.10.22 222
F. frame-relay map ip 10.20.10.21 221 broadcast
G. frame-relay map ip 10.20.10.22 222 broadcast
Answer: C, F, G
Explanation:
In OSPF point-to-muftipoint mode, the routers will automatically identify each neighbor. The election of a designated router (DR) and backup designated router (BDR) are not required. This RFC compliant mode of operation is commonly found in partial mesh topologies, such as hub-and-spoke designs. In the diagram shown in the scenario, router A is the hub.
The frame relay serial interface has one DLCI to each spoke location. DLCI 221 is used by router A to communicate with router C and DLCI 222 is used to communicate with router B. On router A’s serial interface, point-to-muftipoint mode is enabled with the ip ospf network configuration command. The following is the syntax of the ip ospf network command:
ip ospf network [{broadcast I nonbroadcast I point-to-multipoint I point-to-multipoint nonbroadcast}]
The command parameters are as follows:
- broadcast - This mode enables the interface to emulate a LAN. This mode requires a full or partial mesh topology.
- nonbroadcast - This RFC 2328 compliant mode is also referred to as NBMA mode. The neighbors must be statically configured.
- point-to-muftipoint - This RFC 2328 compliant mode is used in partial mesh topologies, such as hub-and-spoke. Routers use additional LSAs to discover neighboring routers instead of manually defining DRs and BDRs. The hub router floods link state updates (LSUs) by duplicating the update to be sent to each routers using the respective DLCI.
- point-to-muftipoint nonbroadcast - This is a Cisco extension to the point-to-muftipoint mode.
This mode is useful when the frame relay virtual circuits do not support broadcast traffic. Neighbors are manually defined.
There is no point-to-point parameter for the ip ospf command. Creating a point-to-point configuration differs in that the point-to-point parameter is executed as a parameter of the command that creates the subinterface that hosts the point-to-point connection as shown below:
Router(config)# interface serial 0.1 point-to-point
When configuring a serial interface without sub-interfaces, OSPF will check the encapsulation to determine the network type. HDLC and PPP default to point-to-point while Frame-Relay encapsulation defaults to nonbroadcast.
The frame-relay map command identifies the mapping between the Layer 3 address (IP address) and the Layer 2 address (DLCI). The frame relay virtual circuits from the hub router are identified as supporting broadcast traffic by using the frame-relay map command with the broadcast keyword.
Objective:
Layer 2 Technologies Sub-Objective:
Explain Frame Relay
References:
Cisco > Home > Support > Support Technology > Support > IP Routing > Configure > Configuration Examples and Technotes > Initial Configurations for OSPF over Frame Relay Subinterfaces Cisco > Cisco IOS Wide-Area Networking Command Reference > frame-relay lapf n201 through fr-atm connect dlci > frame-relay map
When configuring a DMVPN solution, which of the following technologies makes it possible for the spoke to use dynamic IP addressing?
A. IPsec
B. mGRE
C. NHRP
D. Dynamic routing protocols
Answer: C
Explanation:
Next Hop Resolution Protocol (NHRP) allows the spoke routers to register their IP addresses with the NHRP server, which is the hub router. It also allows the spoke routers to then learn the physical IP addresses of the other spoke routers from the hub router, allowing for GRE links to be built dynamically as needed between the spokes. This eliminates the need for the traffic to go through the hub router.
Dynamic Muttipoint VPN (DMVPN) technology leverages the following associated technologies: IPsec
mGRE
Dynamic routing protocols
NHRP
Cisco Express Forwarding
It makes it possible to build the hub router once, and add spokes later, making no additional changes to the hub. The spokes are able to register with the hub and dynamically build their own connections to other spokes using the IP addresses learned from the hub using NHRP. DMVPN also allows IPsec point-to-point GRE tunnels to be built to new spokes with no IPsec peering configuration. The muttipoint GRE technology (mGRE) allows a single physical interface on the hub to be used for all spoke connections.
Finally, the routing protocols used by DMVPN allow the routers to share routing information, while Cisco Express Forwarding (CEF) is a switching technology that improves performance while reducing the load on the CPUs of the routers.
Objective:
VPN Technologies
Sub-Objective:
Describe DMVPN (single hub)
References:
Cisco > Dynamic Muttipoint VPN (DMVPN) Design Guide (Version 1.1) > DMVPN Design Overview
A neighboring EIGRP router fails Its advertised distance (AD) to network 10.10.10.0 was 2 and the feasible distance (FD) was 3.
Which route will be used to route packets destined for network 10.10.10.0 if the other routes have the following feasible and advertised distances respectively to the destination network?
A. FD-6 AD-3
B. FD-4 AD-1
C. FD-5 AD-3
D. FD-4 AD-3
Answer: B
Explanation:
When EIGRP loses it best route, called the successor route, it will then use a feasible successor route, if available, to route the packets to that destination. To be considered a feasible successor, the advertised distance, which is the neighboring router’s distance, needs to be less than the feasible distance, which is the local router’s own metric.
In this scenario, the feasible distance is 3. The only available feasible successors are the ones that have the advertised distance/feasible distance of 1/4 and 2/4.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify policy-based routing
References:
Cisco > Home > Support > Technology Support > IP Routing > Technology Information > Technology White Paper > Enhanced Interior Gateway Routing Protocol > Feasible Distance, Reported Distance, and Feasible Successor
Based on the diagram and the following partial output from Router R2, which networks will be present in the routing table of Router R1?
R2# show run
!
router eigrp 200
network 192.168.5.0
redistribute eigrp 55
!
router eigrp 55
network 10.0.0.0
!
router ospf 1
redistribute eigrp 200
default-metric 50
network 172.50.0.0
A. 192.168.5.0
B. 10.0.0.0
C. 172.50.0.0
D. 192.168.5.0 and 10.0.0.0
Answer: D
Explanation:
The routes that will be present in Router R1 are 192.168.5.0 and 10.0.0.0. According to the output, only the route from EIGRP 55 will be redistributed to EIGRP 200. Therefore, the 10.0.0.0 network will be advertised to Router R1 from Router R2 and the 192.168.5.0 network, which is present in the routing table of Router R2, will be advertised to Router R1.
The 192.168.5.0 network alone would not be correct. The 10.0.0.0 network will be present as well.
The 172.50.0.0 network will not be present because Router 2 is not configured with a redistribution statement for that network. The required statement would be redistribute ospf 1.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify redistribution between any routing protocols or routing sources
References:
Cisco > Home > Support > Technology Support > IP > IP Version 6 > Configure > Configuration Examples and Technotes > Redistributing Routing Protocols
RouterA and RouterB are both in OSPF area 2, and RouterA is connected directly to the backbone. Their router IDs are shown below:
RouterA - 165.165.20.15
RouterB - 165.165.10.12
Which commands should be executed on RouterA and RouterB to create a virtual link between the two routers?
A. RouterA(config-router)# area 2 virtual-link 165.165.10.12
RouterB(config-router)# area 2 virtual-link 165.165.20.15
B. RouterA(config-router)# area 2 virtual-link 165.165.10.12
RouterB(config-router)# area 0 virtual-link 165.165.20.15
C. RouterA(config-router)# area 0 virtual-link 165.165.20.15
RouterB(config-router)# area 2 virtual-link 165.165.10.12
D. RouterA(config-router)# area 0 virtual-link 165.165.10.12
RouterB(config-router)# area 0 virtual-link 165.165.20.15
Answer: A
Explanation:
The area virtual-link command should specify the area to be traversed and the ID of the router to which the router being configured will connect. Therefore, the correct answer is:
RouterA(config-router)# area 2 virtual-link 165.165.10.12
RouterB(config-router)# area 2 virtual-link 165.165.20.15
A virtual link is used to make a virtual connection of an area border router (ABR) to the backbone. It is used in situations where an area does not physically border the backbone area. The virtual link provides logical connectivity of the area to the backbone. If the virtual link appears not to be functional, which would manifest itself in Router A not having all of Router B’s networks in its routing table, the state of the link can be verified on Router A by executing the show ip ospf virtual-link command. An example is shown below. The state of the link as shown in line 1 of the output should be up.
Router/NU show ip ospf virtual-links
Virtual Link to router 172.16.8.2 is up
Transit area 0.0.0.1, via interface Ethernet0, Cost of using 10 Transmit Delay is 1 sec, State POINT _ TO_ POINT
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5 Hello due in 0:00:08
Adjacency State FULL
The configuration below is incorrect because area 0 is referenced in the second line. It should reference area 2, the area being traversed.
RouterA(config-router)# area 2 virtual-link 165.165.10.12
RouterB(config-router)# area 0 virtual-link 165.165.20.15
The configuration below is incorrect because area 0 is referenced in the first line. It should reference area 2, the area being traversed.
RouterA(config-router)# area 0 virtual-link 165.165.20.15
RouterB(config-router)# area 2 virtual-link 165.165.10.12
The configuration below is incorrect because area 0 is referenced in both lines. Both should reference area 2, the area being traversed.
RouterA(config-router)# area 0 virtual-link 165.165.10.12
RouterB(config-router)# area 0 virtual-link 165.165.20.15
If the virtual link is incorrectly configured the following error will be generated:
*Dec 10 00:31.146: %OSPF-4-ERRRCV: Received invalid packet mismatch area ID, from backbone area must be virtual link but not found from 165.165.10.5, Serial 0
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify network types, area types, and router types
References:
Cisco > Home > Support > Technology Support > IP Routing > Design > Design Technotes > What Are OSPF Areas and Virtual Links?
You are troubleshooting a PPPoE connection that is supposed to maintain a connection with the ISP, even if no interesting traffic exists. The configuration of the dialer interface is shown below:
interface dialer 1
ip address negotiated
encapsulation ppp
dialer pool 1
dialer remote-.name remotel
dialer idle-timeout 0 either
dialer string 7135550199
ppp authentication chap
ppp chap hostname DDR
ppp chap password secret
What command should you add to ensure the connection is maintained in the absence of interesting traffic?
A. dialer -group
B. dialer persistent
C. dialer list
D. dialer string
Answer: B
Explanation:
- The dialer persistent command is used to specify that the connection stays up even in the absence of interesting traffic. Interesting traffic is user-defined traffic that triggers a call to the remote end. Were it present in the configuration, the section would appear as follows:
interface dialer 1
ip address negotiated encapsulation ppp
dialer pool 1
dialer remote-name remotel dialer idle-timeout 0 either dialer string 7135550199 dialer persistent
ppp authentication chap ppp chap hostname DDR ppp chap password secret
- The dialer-group command is assigns the dialer interface to a dialer group. It is an optional setting, and does not appear in this configuration.
- The dialer-list command is used to specify an access list that defines interesting traffic. It is an optional setting, and would NOT be a part of a configuration that does not maintain the connection based on interesting traffic. If you use dialer persistent, then you don’t need to use dialer-list. The dialer list defines interesting traffic, while dialer persist keep the connection up in the absence of interesting traffic.
- The dialer string command is used to define the number to call to make the connection. It is present in the configuration in the scenario, and specifies the number 713 555 0199.
Objective:
Layer 2 Technologies Sub-Objective:
Configure and verify PPP
References:
Cisco Dial Configuration Guide, Release 15.05 > Part 5: Dial-on-Demand Routing Configuration > Configuring Peer-to-Peer DDR with Dialer Profiles Cisco Press > Articles > Cisco Network Technology > General Networking > End-to-End DSL Architectures
Which show command displays entries in a router’s Border Gateway Protocol (BGP) table?
A. show ip bgp
B. show ip bgp table
C. show ip bgp topology
D. show ip bgp summary
Answer: A
Explanation:
The correct command is show ip bgp.
The BGP table lists all the paths that the BGP router has learned. Each destination network listed might have multiple possible paths listed. Given that the criteria are met for each destination network, BGP will choose a path to put in the IP routing table.
The BGP table is in many ways analogous to EIGRP’s topology table in that it lists many known paths, not just the best path. Below is an example partial output of the show ip bgp command:
Router54 show ip bgp
BGP table version is 5, local router ID is 20.0.33.34
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*>
- 0.0.0
- 0.0.0
0
32768
?
*
- 0.0.0
- 0.33.40
10
0
35
?
*>
0.0.0.0
0
32768
?
*>
- 0.0.0
- 0.33.40
10
0
35
?
1r>
0.0.0.0
0
32768
?
*>
- 168.0.0/16
- 0.33.40
10
0
35
?
The following facts can be determined from this output:
• All of the routes were redistributed into BGP from an IGP. In the status column (located to the left of the Network column and to right of the column where some lines have a > symbol) is a column that is either blank or has an i symbol. In this case, all of the columns are blank. If the status column is blank, then BGP learned the route from an external peer. If it has an i symbol, an iBGP neighbor advertised this path to the router. It was learned from an Interior Gateway Protocol (IGP) and was advertised as a result of executing a network statement on the neighbor under the router bgp context as shown below adding the 30.0.0.0 network under BGP 100.
R4(config)#router bgp 100 R4(config-router)#network 30.0.0.0
- Four routes will be installed in the routing table. These routes have both an *symbol and a > symbol.
- I in the status column. The *symbol indicates that the next hop is valid and the > symbol indicates that this is the best route.
The output is slightly different if you specify the network that you are interested in, as shown below in the show ip bgp 214.5.98.0 command output:
Router 411 show ip bgp 214.5.98.0
BGP routing table entry for 241.5.98.0/24, version 48
Paths: (2 available, best 11, table Default-IP-Routing-Iable) Not advertised to any peer
5760
192.168.1.1 (metric 886) from 192.168.1.1 (192.168.1.1) Origin IGP, metric 1652, localpref 100, valid, internal, best
This output focuses solely on the route to the network 214.5.98.0 and provides the following pieces of information:
- The neighbor that sent this route is at 192.168.11
- The AS of the network where 214.5.98.0 is located is 5760
- The IGP metric to reach the neighbor that sent this route is 886, as shown by the text 192.168.11 (metric 886)
- The complete metric to 214.5.98.0 is 1652, as shown in the last line by Origin IGP, metric 1652
The commands show ip bgp table and show ip bgp topology are not valid Cisco commands. The show ip bgp summary command displays the status of BGP connections.
Objective:
Layer 3 Technologies
Sub-Objective:
Explain BGP attributes and best-path selection
References:
Cisco IOS Master Command List, Release 12A > I through q > Cisco IOS IP Routing: BGP Command Reference > show ip bgp
Which of the following statements is NOT true of NPTv6?
A. is transport agnostic
B. translates the entire IPv6 address to another IPv6 address
C. is check sum neutral
D. translates only the IPv6 prefix
Answer: B
Explanation:
Network Prefix Translation (NPTv6) is a stateless method of translating the prefix of a received IPv6 address to another prefix without changing the host portion of the IPv6 address. Some of its characteristics are:
• It supports both transports that perform checksums on the IP header and those that do not.
• It provides a 1 to 1 relationship between the inside and outside prefixes.
• It translates only the prefix, and not the entire address.
Objective:
Infrastructure Services
Sub-Objective:
Describe IPv6 NAT
References:
Cisco > Publications and Merchandise > The Internet Protocol Journal > Issues > Volume 14, Number 2, June 2011 > IPv6 Site Muttihoming
Howfunky…a place with useless technical content!>IPv6 to IPv6 Network Prefix Translation or NPTv6
You are planning the configuration of Easy Virtual Networking (EVN).
Which of the following statements is true of an interface that will be an EVN trunk?
A. It must support 802.1q encapsulation
B. The interface can also be configured for VRF-Lite
C. The interface will support OSPFv3
D. The interface can support RIP
Answer: A
Explanation:
The interface must be able to support 802.1 q encapsulation. The EVN trunk carries the traffic of multiple virtual routing and forwarding (VRF) instances, with the traffic of each instance tagged with an ID called the virtual network tag. Since the VLAN ID field of an 802.1 q encapsulated packet is used for this ID, the link must be one that supports 802.1 q.
Easy Virtual networking is a technology that allows for the creation of separate networks with separate routing tables and routing instances using the same physical topology. The IP addressing for the networks can even overlap with no problem. The networks are kept separate using the network ID tags in a similar fashion to the way switches keep VLANs separate by using VLAN tags.
An EVN trunk interface cannot also be configured for VRF-Lite. VRF-Lite is an earlier technology that accomplishes the same goal, but lacks the simplicity of EVN. Neither RIP nor OSPFv3 is supported in Easy Virtual Networking EVN at all.
Objective:
VPN Technologies
Sub-Objective:
Describe Easy Virtual Networking (EVN)
References:
Cisco > Easy Virtual Network Configuration Guide, Cisco IOS XE Release 3S > Overview of Easy Virtual Network
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
Answer: C
Explanation:
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 10.1.0.0116, 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
Click the Exhibit(s) button to view an EIGRP network. The partial output of the show running-config command on the rtrB router is as follows:
rtrB# show running-config
!
ip prefix-list blk A deny 172.161.0.0/16 ge 24 le 30
ip prefix-list blk A permit 0.0.0.0/0 le 32
!
router eigrp 101
network 172.161.247.0 0.0.0.255
network 172.161.64.0 0.0.0.15
distribute-list prefix blk A out
auto-summary
!
Which of the following subnets are blocked through the Fa0/0 interface of rtrB while sending updates to rtrC? (Choose all that apply.)
A 172.161.9.0/24
B 172.161.35.0/18
C 172.161.64.0/28
D 172.161.88.0/22
E 172.161.111.0/25
F 172.161.247.0/30
Answer: A, E, F
Explanation:
The 172.161.9.0/24, 172.161.111.0/25 and 172.161.247.0/30 subnets are blocked through the Fa0/0 interface of rtrB while sending updates to rtrC. The following lines in the output create an IP prefix list named blk_A:
ip prefix-list blk_A deny 172.161.0.0/16 ge 24 le 30
ip prefix-list blk_A permit 0.0.0.0/0 le 32
The blk_A list blocks the subnets that exactly match the first 16 most significant bits as 172.161.0.0. The ge keyword indicate that the subnet mask for the 172.161.0.0 subnets must be greater than or equal to 24 bits. Similarly, the le keyword indicates that the mask for the 172.161.0.0 subnets should be less than or equal to 30 bits. Therefore, all subnets of 172.161.0.0 network with masks 24, 25, 26, 27, 28, 29,
and 30 are blocked.
The second line permits all other routes to be passed on. The subnets that match the blk_A prefix list are 172.161.9.0/24, 172.161.111.0/25, 172.161.247.0/30, and 172.161.64.0/28.
The line distribute-list prefix blk_A out indicates that the distribute-list command applies the blk_A prefix list to all the outgoing interfaces. This implies that if rtrB receives an update about the 172.161.9.0/24, 172.161.111.0/25, 172.161.247.0/30 or 172.161.64.0/28 subnets, they are blocked. In this case, the 172.161.64.0/28 is not blocked through the Fa0/0 interface to rtrC because it is directly connected.
The 172.161.35.0/18 and 172.161.88.0/22 subnets are not blocked through the Fa0/0 interface of rtrB to rtrC. This is because both these subnets are outside the range of prefix masks 24 through 30; hence,
these two subnets are allowed through the Fa0/0 interface.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify filtering with any protocol
References:
Cisco > Home > Support > Technology Support > IP > IP Routing > Technology Information > Technology Technotes > Filtering Routing Updates on Distance Vector IP Routing Protocols
Cisco > Cisco IOS IP Routing: Protocol-Independent Command Reference > distribute-list in
Cisco > Cisco IOS IP Routing: BGP Command Reference > ip prefix-list
OSPF area border routers (ABRs) advertise a default route to stub and totally stubby areas.
Which command is the BEST command to configure a cost of 25 for the default route advertised to area 1?
A. Router(config-router)# area 1 cost 25
B. Router(config-router)# area 1 default 25
C. Router(config-router)# area 1 default-cost 25
D. Router(config-router)# area 1 default-route-cost 25
Answer: C
Explanation:
The correct answer is area 1 default-cost 25. Even though another option (area 1 default 25) is a configurable abbreviation for the command, the more correct answer explicitly specifies the default-cost parameter. The correct syntax for the area default-cost command is shown below:
Router(config-router)# area area-id default-cost cost
If you have multiple border routers between two areas, you might prefer one exit-point router over the other for that area. By configuring one with a lower cost than the other, it will become the preferred exit point. If that router or its links were to fail, then the routers interior to the area would route through the second-best exit point. You could also set the default costs to values that are close to achieve better load balancing.
The default default-cost is 1. Please see the network shown in the graphic.
All traffic will follow the path indicated by the curved arrow to the preferred ABR.
Objective:
Layer 3 Technologies
Sub-Objective:
Configure and verify OSPF path preference
References:
Cisco IOS Master Command List, Release 12.4 > a through b > area default-cost
