Redistribute Questions

Here you will find answers to Redistribute Questions

Question 1

Refer to the exhibit. Which statement is true?

hostname RAR1 ! ! router bgp 100 neighbor 172.16.1.2 remote-as 200 neighbor 172.16.1.2 distribute-list 101 in ! access-list 101 permit ip 10.10.0.0 0.0.31.255 0.0.0.0 0.0.0.0

A. Router RAR1 will accept only route 10.10.0.0/19 from its BGP neighbor.
B. Router RAR1 will send only route 10.10.0.0/19 to its BGP neighbor.
C. Only traffic with a destination from 10.10.0.0/19 will be permitted.
D. Only traffic going to 10.10.0.0/19 will be permitted.

 

Answer: A

Question 2

Refer to the exhibit. Which three statements accurately describe the result of applying the exhibited route map? (Choose three)

router eigrp 1 redistribute ospf 1 route-map ospf-to-eigrp default-metric 20000 2000 255 1 1500 ! ! route-map ospf-to-eigrp deny 10 match tag 6 match route-type external type-2 ! route-map ospf-to-eigrp permit 20 match ip address prefix-list pfx set metric 40000 1000 255 1 1500 ! route-map ospf-to-eigrp permit 30 set tag 8

A. The map prohibits the redistribution of all type 2 external OSPF routes with tag 6 set.
B. The map prohibits the redistribution of all type 2 external OSPF routes.
C. The map redistributes into EIGRP all routes that match the pfx prefix list and the five metric values 40000, 1000, 255, 1, and 1500.
D. The map prohibits the redistribution of all external OSPF routes with tag 6 set.
E. All routes that do no match clauses 10 and 20 of the route map are redistributed with their tags set to 8.
F. The map permits the redistribution of all type 1 external OSPF routes.

 

Answer: A E F

Explanation

In the route-map:

route-map ospf-to-eigrp deny 10
match tag 6
match route-type external type-2

The deny clause rejects route matches from redistribution. If several match commands are present in a clause, all must succeed for a given route in order for that route to match the clause (in other words, the logical AND algorithm is applied for multiple match commands). In this question, both the “match tag 6” and “match route-type external type-2” must be matched for this route to be denied -> A is correct.

If a match command is not present, all routes match the clause. In this question, all routes that reach clause 30 match and their tags are set to 8 -> E is correct.

If a route is not matched with clause 10 or 20 then it will be matched with clause 30 for sure -> F is correct.

Note: Route-maps that are applied to redistribution behave the same way as ACLs: if the route does not match any clause in a route-map then the route redistribution is denied, as if the route-map contained deny statement at the end.

(Reference: http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a008047915d.shtml)

Question 3

Refer to the exhibit. On the basis of the information in the exhibit, which two statements are true? (Choose two)

A. The output was generated by entering the show ip bgp command on the ISP router.
B. The output was generated by entering the show ip bgp command on the SanJose1 router.
C. The serial0/0/1 interface on the ISP router has been configured with the set metric 50 command.
D. The serial 0/0/1 Interface on the ISP router has been configured with the set metric 75 command.
E. When traffic is sent from the ISP to autonomous system 64512, the traffic will be forwarded to SanJose1 because of the lower MED value of SanJose1.
F. When traffic is sent from the ISP to autonomous system 64512, the traffic will be forwarded to SanJose2 because of the higher MED value of SanJose2.

 

Answer: A E

Explanation

From the output, we notice that the “local router ID” is 192.168.100.1 which is an interface on ISP router -> A is correct.

The show ip bgp command is used to display entries in the Border Gateway Protocol (BGP) routing table

Multi-Exit Discriminator (MED) is used when we have multiple entry points (connections) to another AS. A lower MED value is preferred over a higher value. Notice that the comparison between the MED only occurs if the first AS is the same in two (or more) paths. In this question, the first AS is 64512 which is the same -> the comparison can occur.

From the output, we learn that ISP router is receiving the 172.16.0.0 network from SanJose1 (192.168.1.6) with a metric of 50 and from SanJose2 (192.168.1.2) with a metric of 75. Also note that BGP has chosen the best path 192.168.1.6 to the 172.16.0.0 network (the “>” indicates it is the best path). The Weight, Local Preference (LocPrf) and AS-Path values between two next hops (192.168.1.2 & 192.168.1.6) are the same so we can deduce the traffic from ISP is sent from the ISP to SanJose1 because of the lower MED value.

Note: An entry of 0.0.0.0 in the “Next Hop” indicates that the router has some non-BGP routes to this network.

Question 4

Refer to the exhibit. Routers R1 and R2 have been configured to operate with OSPF. Routers R1 and R3 have been configured to operate with RIP. After configuring the redistribution between OSPF and RIP on R1, no OSPF routes are distributed into RIP. What should be done to correct this problem?

A. The redistribution command should be reentered with the match route-type parameter included.
B. The redistribution command should be reentered with the route-map map-tag parameter included.
C. The redistribution command should be reentered with the metric metric-value parameter included.
D. Routes will first need to be distributed into another protocol, and then into RIP.

 

Answer: C

Explanation

Notice that RIP metric is based on hop count only, and the maximum valid metric is 15. Anything above 15 is considered infinite. By default, when no metric is assigned when redistributing from EIGRP, OSPF, IS-IS, BGP into RIP, the default metric will be infinite. Therefore we must define a metric that is understandable to the receiving protocol. Usually, we should use a small value (like 1, 2, 3) so that after redistributing, that route can be advertised through many routers (because the limit is 15).

Question 5

router eigrp 123 redistribute ospf 123 network 116.16.35.0 0.0.0.255 network 130.130.0.0 auto-summary ! router ospf 123 log-adjacency-changes network 116.16.34.0 0.0.0.255 area 0 neighbor 116.16.34.4

Refer to the exhibit. Why are the EIGRP neighbors for this router not learning the routes redistributed from OSPF?

A. Redistribution must be enabled mutually (in both directions) to work correctly.
B. Auto-summary causes the OSPF routes redistributed into EIGRP to be summarized; thus the OSPF network 116.16.34 is summarized to 116.34.0.0, which is already covered by the EIGRP protocol.
C. Default metrics are not configured under EIGRP.
D. Both routing protocols must have unique autonomous system numbers for redistribution to function correctly.

 

Answer: C

Explanation

Same as RIP, when redistribute into EIGRP from OSPF, the default metric is infinite -> We must set a seed metric when redistributing into EIGRP. Below lists the default seed metrics when redistributing from a routing protocol into another:

Redistributed Protocol	Default Seed Metric
RIP	Infinity
IGRP/EIGRP	Infinity
OSPF	20 for all (except for BGP, which is 1)
BGP	is set to IGP metric value

Question 6

If a metric is not specified for routes that are redistributed into OSPF, the default metric that is assigned to the routes is 20, except for redistributed BGP routes. What is the metric that is assigned to redistributed BGP routes?

A. 0
B. 1
C. 10
D. 200

 

Answer: B

Explanation

Same explanation of Question 5

Question 7

During a redistribution of routes from OSPF into EIGRP, an administrator notices that none of the OSPF routes are showing in EIGRP. What are two possible causes? (Choose two)

A. incorrect distribute lists have been configured
B. missing ip classless command
C. CEF not enabled
D. no default metric configured for EIGRP

 

Answer: A D

Explanation

An incorrect distribute list can filter out updates therefore none of the OSPF routes are showing in EIGRP -> A is correct.

The default metric when redistributing into EIGRP is infinite so we must specify a seed metric for EIGRP to work with -> D is correct.

Question 8

During the redistribution process configured on RTA, some of the EIGRP routes, such as 10.1.1.0/24 and 10.2.2.0/24, are not being redistributed into the OSPF routing domain. Which two items could be a solution to this problem? (Choose two)

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

 

Answer: C D

Explanation

The AS of EIGRP in the output above is not correct and we need to fix it into “eigrp 1”. Also, some of EIGRP routes, such as 10.1.1.0/24 and 10.2.2.0/24 are subnets so we must use the keyword “subnets” so that OSPF can see these routes. The full commands should be:

router ospf 1
redistribute eigrp 1 metric 20 metric-type 1 subnets

Question 9

You want the redistributed EIGRP AS 10 routes to have an administrative distance of 121 when they appear as RIP routes in the routing table of A1. Which command should you use on a router to accomplish this goal?

A. redistribute eigrp 10 metric 121
B. redistribute rip metric 121
C. default-metric 121
D. distance 121 10.1.1.6 0.0.0.0

 

Answer: D

Question 10

Refer to the exhibit. Which three commands should be used on router B1 to redistribute the EIGRP AS 10 routes into RIP? (Choose three)

A. router rip
B. router eigrp 10
C. redistribute eigrp 10
D. redistribute rip
E. default-metric 10000 100 255 1 1500
F. default-metric 5

 

Answer: A C F