Cisco CCNP 300-410 Questions & Answers

• Question 31:

  Your network has an OSPF area that connects to an EIGRP area at two points, Router A and Router B. You directed your assistant to set up these two routers in order to have traffic load-balanced between the two entry points. However, you discover that all traffic is going through Router A. When you view the results of the show run command for each device, you get the partial output shown below:

  

  What action should be performed to make traffic use both routes to the EIGRP area?

  A. change the metric for EIGRP to 50 on Router A

  B. change the metric for EIGRP to 45 on Router B

  C. change the metric type to Type 1 on Router A

  D. change the metric type to Type 1 on Router B

  Correct Answer: A

  You should change the metric for EIGRP to 50 on Router A. The metric can be defined when configuring the redistribution of one routing protocol into another. A lower metric will cause traffic to be routed in that direction. Therefore, to make

  the paths from the two routers equal, you should raise the metric on Router A to 50 to match that of Router B.

  You should not lower the metric on Router B to 45. It will still be a higher metric than that of A and traffic will still go in that direction.

  You should not change the metric type on either router. The metric type determines whether the downstream OSPF routers should add their cost to the total cost to get to the ASBR when computing cost. In this scenario, Router A and Router

  B are both ASBRs. When set to Type 1, downstream OSPF routers do add their metric. With Type 2, they simply use the configured metric. If you want true load balancing, you should leave the metric type set to Type 2, since you have no

  information on the cost from the other routers to the ASBRs. However, when Type 1 is used, you must also take into consideration the metric from the other routers to the ASBR when determining the true cost to leave the OSPF area.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify redistribution between any routing protocols or routing sources

  References:

  Home > Support > Technology Support > IP > IP Routing > Design > Design Technotes > Redistributing Routing Protocols

  Cisco > Support > Technology Support > IP > IP Routing > Design > Design Technotes > Route Selection in Cisco Routers > Document ID: 8651

• Question 32:

  For a non-ISP autonomous system (AS), which combination of two conditions will require redistribution from BGP into Interior Gateway Protocol (IGP)? (Choose two.)

  A. All routers run BGP.

  B. Not all routers run BGP.

  C. No knowledge of external routes is required inside the AS.

  D. Routers inside the AS require knowledge of external routes.

  Correct Answer: BD

  For non-ISP autonomous systems (AS), redistribution into IGP is required when BOTH of the following conditions exist:

  Not all routers run BGP

  Knowledge of external routes is required inside the AS

  Note: Redistribution of any BGP routes into your IGP can cause serious problems, even if your internal routers can handle the load. This should be done rarely, if at all. If you do decide to do this, configure heavy filtering to allow only very few

  routes into OSPF or EIGRP so as not to overwhelm those protocols. For instance, do it only for a select group of networks for which optimal routing is critical.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify redistribution between any routing protocols or routing sources

  References:

  Cisco > Support > Technology Support > IP > IP Routing > Design > Design Technotes > BGP Case Studies > Document ID: 26634 > Static Routes and Redistribution Cisco > Cisco IOS IP Routing: BGP Configuration Guide, Release 12.4 >

  Cisco BGP Overview > Information About Cisco BGP > BGP Autonomous Systems

• Question 33:

  You need to configure eBGP on the rtrA and rtrB routers, as shown in the following image:

  

  You have configured eBGP on rtrA through the following commands:

  rtrA(config)# router bgp 501 rtrA(config)# neighbor 201.60.3.2 remote-as 505

  While configuring eBGP on rtrB, you need to ensure that updates about the 192.168.58.0/24 and the 192.168.127.0/24 subnets are sent to rtrA with a metric of 300. In addition, rtrB should send updates about the 172.161.94.0/24 subnet are sent with a metric of 500.

  Which of the following set of commands would NOT be part of the set used to correctly configure eBGP on rtrB?

  A. access-list 1 permit 192.168.0.0 0.0.255.255 access-list 2 permit 172.161.94.0 0.0.0.255 router bgp 505 neighbor 201.60.3.1 remote-as 501 neighbor 201.60.3.1 route-map change_parameters in

  B. access-list 1 permit 192.168.0.0 0.0.255.255 access-list 2 permit 172.161.94.0 0.0.0.255 router bgp 505 neighbor 201.60.3.1 remote-as 501 neighbor 201.60.3.1 route-map change_parameters out

  C. route-map change_parameters permit 10 match ip-address 2 set metric 500

  D. route-map change_parameters permit 20 match ip-address 1 set metric 300

  Correct Answer: A

  The following command set would NOT be used because it only applies the access list route-map change_parameters inbound instead of outbound, as would be required:

  

  The ACL 1 allows the 192.168.58.0/24 and the 192.168.127.0/24 subnets, while the ACL 2 allows the 172.161.94.0/24 subnet. The neighbor route-map command specifies a route-map named change_parameters for the 201.60.3.1 BGP

  peer. The out keyword at the end of the command indicates that the route-map is applied only to the updates sent by rtrB, and not received by rtrB.

  In the following command, the route map change_parameters is defined with the permit keyword. The permit keyword indicates that if a match occurs, the actions specified in the set sub-command are executed:

  route-map change_parameters permit 10

  match ip-address 2

  set metric 500

  In this case, this command checks if the IP address of the subnets advertised to rtrA is in the 172.161.94.0/24 subnet (specified by ACL 2). If the IP address matches, then the metric of those routes are set to 500.

  In the following command, the route map change_parameters is defined with the permit keyword:

  route-map change_parameters permit 20

  match ip-address 1

  set metric 300

  In this case, this command checks if the IP address of the subnets advertised to rtrA is in the 192.168.58.0/24 or the 192.168.127.0/24 subnets (specified by ACL 1) If the IP address matches, then the metric of those routes are set to 300.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify eBGP (IPv4 and IPv6 address families)

  References:

  Cisco > Home > Support > Technology Support > IP > IP Routing > Design > Design Technotes > BGP Case Studies > Route Maps

  Cisco > Cisco IOS IP Routing: Protocol-Independent Command Reference > route-map

• Question 34:

  

  Routers R1 and R2 are being added to the network shown in the exhibit.

  The addresses of their respective interfaces have already been configured as follows:

  R1: E0 192.168.4.5/30

  R2: E0 192.168.4.6/30

  R2: E1 192.168.72.6/30

  You have been assigned to complete the following as a part of implementing OSPF area 5:

  The E0 interface on R1 should be in area 5.

  The E0 interface on R2 should be in area 5.

  The mask used with the OSPF configuration should only include the addresses for R1 and R2. Area 5 should not allow any external or inter-area routes (except for the default route).

  Which commands are required to accomplish this set of requirements? (Choose all that apply.)

  A. R1# configure terminal R1(config)# router OSPF 1 R1(config-router)# network 192.168.4.4 0.0.0.3 area 5 R1(config-router)# area 5 stub R1(config-router)# end R1# copy running-config startup-config

  B. R1# configure terminal R1(config)# router OSPF 1 R1(config-router)# network 192.168.4.4 0.0.0.3 area 5 R1(config-router)# area 5 stub no-summary R1(config-router)# end R1#copy running-config startup-config

  C. R1# configure terminal R1(config)# router OSPF 1 R1(config-router)# network 192.168.4.4 0.0.0.4 area 5 R1(config-router)# area 5 stub R1(config-router)# end R1# copy running-config startup-config

  D. R2# configure terminal R2(config)# router OSPF 1 R2(config-router)# network 192.168.4.4 0.0.0.3 area 5 R2(config-router)# area 5 stub no-summary R2(config-router)# end R2# copy running-config startup-config

  E. R2# configure terminal R2(config)# router OSPF 1 R2(config-router)# network 192.168.4.4 0.0.0.3 area 0 R2(config-router)# area 0 stub no-summary R2(config-router)# end R2# copy running-config startup-config

  F. R2# configure terminal R2(config)# router OSPF 1 R2(config-router)# network 192.168.4.4 0.0.0.3 area 5 R2(config-router)# area 5 stub R2(config-router)# end R2# copy running-config startup-config

  Correct Answer: AD

  The following set of commands will configure R1 properly and satisfy the requirements:

  R1# configure terminal

  R1(config)# router OSPF 1

  R1(config-router)# network 192.168.4.4 0.0.0.3 area 5

  R1(config-router)# area 5 stub

  R1(config-router)# end

  R1# copy running-config startup-config

  The configure terminal command enters global configuration mode, from which the router ospf 1 command can be executed to enable OSPF process 1. The network command allows the192.168.4.4/30 network to join OSPF area 5 and uses

  a wildcard mask (0.0.0.3) that only includes the E0 interfaces on R1 and R2. The area 5 stub command configures R1 as an internal router in a totally stubby area, which is necessary because no external or inter-area routes are allowed. The

  final two commands exit OSPF configuration mode and save the configuration.

  The following set of commands will configure R2 properly and satisfy the requirements:

  R2# configure terminal

  R2(config)# router OSPF 1

  R2(config-router)# network 192.168.4.4 0.0.0.3 area 5

  R2(config-router)# area 5 stub no-summary

  R2(config-router)# end

  R2# copy running-config startup-config

  The configure terminal command enters global configuration mode, from which the router ospf 1 command can be executed to enable OSPF process 1. The network command allows the192.168.4.4/30 network to join OSPF area 5, and uses

  a wildcard mask (0.0.0.3) that only includes the E0 interfaces on R1 and R2. The area 5 stub no-summary command configures R2 as an area border router (ABR) in a totally stubby area, which is necessary because no external or inter-area

  routes are allowed. The final two commands exit OSPF configuration mode and save the configuration.

  The wildcard mask on both network statements, 0.0.0.3, is the wildcard equivalent of a 255.255.255.252 mask (/30). When used with the network address 192.168.4.4, this mask will only allow two addresses in the area, 192.168.4.5 and

  192.168.4.6, as per the scenario requirements.

  The command set that executes the area 5 stub no-summary command on router R1 is incorrect because R1 is an internal router and does not require the no-summary keyword. The no-summary keyword is only required on the ABR when

  configuring a totally stubby area.

  The command set that executes the network 192.168.4.4 0.0.0.4 area 5 command on router R1 has the wrong wildcard mask.

  The command set that executes the network 192.168.4.4 0.0.0.3 area 0 command on router R2 is incorrect because the area should be area 5, not area 0.

  The command set that executes the area 5 stub command on router R2 is incorrect becauseR2 is an ABR router and requires the no-summary keyword when configuring a totally stubby area.

  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? > What Are Areas, Stub Areas, and Not-So-Stubby Areas? Cisco > Cisco IOS IP Routing: OSPF

  Command Reference > area stub

• Question 35:

  If the following protocols are redistributed into OSPF, which protocol will receive a metric of 1 if none is specified, rather than the default metric of 20?

  A. EIGRP

  B. RIP

  C. IGRP

  D. BGP

  Correct Answer: D

  Border Gateway Protocol (BGP) routes that are redistributed into OSPF will be marked with a metric of 1 if no other metric is specified. All other routing protocols will receive a metric of 20 when redistributed into OSPF.

  A metric can be manually specified when redistributing the route, as shown below:

  router5(config)# router ospf 10

  router5(config-router)# redistribute bgp 120 metric 5

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify redistribution between any routing protocols or routing sources

  References:

  Cisco Press > Articles > Network Technology > General Networking > Cisco OSPF Route Redistribution Cisco > Support > Technology Support > IP > IP Routing > Design > Design Technotes > Redistributing Routing Protocols > Document

  ID: 8606

• Question 36:

  Which command can you use to display the area border routers (ABRs) and the routes to them?

  A. show ip ospf dr

  B. show ip opsf bdr

  C. show ip ospf database

  D. show ip ospf border-routers

  Correct Answer: D

  The correct answer is show ip ospf border-routers. The following commands are available to verify OSPF configurations:

  show ip ospf border-routers - displays internal ISPF routing table entries for an ABR. show ip ospf virtual-links - displays the current state of OSPF virtual links. show ip ospf - displays information about the router's role and each area to which

  the router is connected. show ip ospf database - displays the contents of the router's topological database. Note that a number of keywords can be used with the show ip ospf database command to get specific information.

  The command show ip ospf dr is not correct because dr is not a parameter of the show ip ospf command.

  The command show ip ospf bdr is not correct because bdr is not a parameter of the show ip ospf command.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

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

  References:

  Cisco > Cisco IOS IP Routing: OSPF Command Reference > show ip ospf border-routers

• Question 37:

  Consider the following commands:

  RouterA(config)# router ospf 10 RouterA(config-router)# redistribute eigrp 20 metric 30 What does the value of 30 represent?

  A. It identifies the seed metric associated with OSPF routes that are redistributed into EIGRP.

  B. It identifies the seed metric associated with EIGRP routes that are redistributed into OSPF.

  C. It identifies the amount that the existing EIGRP metric will increment as it is redistributed into OSPF.

  D. It specifies that routes that contain metrics of less than 30 will be redistributed from OSPF into EIGRP.

  Correct Answer: B

  The value 30 represents the seed metric for routes that are redistributed from EIGRP into OSPF.

  When configuring the OSPF process, the redistribute command is used to identify the source protocol, its AS or process ID, and several other optional parameters, such as metric. The default seed metric for all routing protocols except BGP is

  20. When redistributing BGP, the default seed metric is 1.

  It does not identify the seed metric associated with OSPF routes that are redistributed into EIGRP. The command is redistributing EIGRP into OSPF, not OSPF into EIGRP.

  It does not identify the amount that the existing EIGRP metric will increment as it is redistributed into OSPF. A seed metric value is an absolute value not incremental.

  It does not specify that routes that contain metrics of less than 30 will be redistributed from OSPF into EIGRP.

  It not used to filter routes.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Configure and verify redistribution between any routing protocols or routing sources

  References:

  Cisco > Cisco IOS IP Routing: Protocol-Independent Command Reference > redistribute (ip)

• Question 38:

  Examine the sample output of the show ip eigrp topology command.

  

  The network 65.0.0.0 is one of the advertised networks in the routing table. What does the value 128256 represent?

  A. The advertised distance

  B. The feasible distance

  C. The administrative distance

  D. The hop count

  Correct Answer: A

  The number 128256 after the advertisement for network 65.0.0.0 represents the advertised distance. The advertised distance is the metric that the neighboring router advertised to the local router.

  The feasible distance is the metric that the local router would advertise to the next router. Feasible distance is represented by the number preceding the advertised distance number in the output.

  The administrative distance is a number that represents the trustworthiness of a routing protocol. It allows a router to decide which routing protocol's route to use in the event that more than one protocol advertises a route to the same network.

  The administrative distance is not shown in the output of the show ip eigrp topology command.

  Hop count is a simple metric that RIP uses to compare multiple routes to the same network.

  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 Cisco >

  Cisco IOS IP Routing: EIGRP Command Reference > show ip eigrp topology

• Question 39:

  Which parameter does EIGRP use to compute the bandwidth part of the metric?

  A. The maximum bandwidth link in the path, in kilobits per second

  B. The minimum bandwidth link in the path, in kilobits per second

  C. The average bandwidth of all the links in the path, in kilobits per second

  D. The average bandwidth of all the links in the path, in kilobytes per second

  Correct Answer: B

  The minimum bandwidth link, in kilobits per second, is used in the EIGRP metric calculation, because this is the limiting factor in the overall speed of delivery over the path.

  BW = (10,000,000 / bandwidth in Kbps) x 256

  Delay = (delay in microseconds / 10) x 256

  The formula for calculating the EIGRP metric is shown below:

  [K1 x BW + (K2 X BW) / (256 - load) + K3 x delay] X [K5 / (reliability + K4)]

  You should note, however, that when K5 = 0 (as it is by default), a slightly different formula applies.

  When K5 = 0, the EIGRP metric is [K1 X BW + (K2 X BW) / (256 - load) + K3 x delay]

  By default, K1 = 1, K3 = 1, and K2, K4, and K5 = 0.

  Therefore, the default EIGRP metric is BW + Delay, where "BW" and "Delay" are determined according to the formula above.

  The final formula is shown below:

  [10,000,000 / (bandwidth in Kbps) + (delay in microseconds) / 10] * 256

  These usually are derived from the values listed in the show interfaces command.

  Objective:

  Layer 3 Technologies

  Sub-Objective:

  Describe and optimize EIGRP metrics

  References:

  Cisco > Home > Support > Technology Support > IP Routing > Technology Information > Technology White Paper > Enhanced Interior Gateway Routing Protocol > Using The Metrics

• Question 40:

  Which of the following statements is NOT true about BGP peers?

  A. eBGP peers use TCP to communicate

  B. eBGP peers 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

  Correct Answer: C

  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