300-410 Route Redistribution — Timed 15 Questions

Question 1

A network engineer is troubleshooting a route redistribution issue between OSPF and EIGRP. Routers R1 (OSPF) and R2 (EIGRP) are redistributing routes into each other. The engineer notices that some OSPF external routes are not appearing in the EIGRP topology table on R2, although the redistribution is configured. The show ip eigrp topology command on R2 does not list the missing prefixes. What is the most likely cause?

Accepted Answer

The redistribute ospf command under EIGRP is missing the match external keyword.. When redistributing from OSPF into EIGRP, by default only OSPF internal routes are redistributed; external OSPF routes (type 5 or 7) are not included unless the match external keyword is specified. This explains why some routes are missing.

Answer

The redistribute ospf command under EIGRP is missing the match internal keyword.

Answer

The OSPF process on R1 has a route filter blocking external routes.

Answer

EIGRP has a lower administrative distance than OSPF, causing route suppression.

Question 2

A network engineer is troubleshooting a route redistribution issue between EIGRP and OSPF. Routers R1 (EIGRP) and R2 (OSPF) are redistributing routes. The engineer notices that some EIGRP external routes (redistributed into EIGRP from another protocol) are not appearing in the OSPF database on R2. The show ip ospf database external command on R2 does not list these prefixes. What is the most likely cause?

Accepted Answer

The redistribute eigrp command under OSPF is missing the match external keyword.. When redistributing from EIGRP into OSPF, by default only EIGRP internal routes are redistributed; EIGRP external routes are not included unless the match external keyword is specified.

Answer

The redistribute eigrp command under OSPF is missing the subnets keyword.

Answer

EIGRP has a higher administrative distance than OSPF, causing route suppression.

Answer

The OSPF process on R2 has a distribute-list blocking these routes.

Question 3

A network engineer is troubleshooting a route redistribution issue between two OSPF processes. Router R1 runs OSPF process 1 and OSPF process 2, and redistributes routes between them. The engineer notices that routes from OSPF process 1 are not appearing in the OSPF database of process 2, even though the redistribute command is configured. The show ip ospf database command on R1 for process 2 shows no external routes. What is the most likely cause?

Accepted Answer

The redistribute ospf 1 command under OSPF process 2 is missing the subnets keyword.. When redistributing between OSPF processes, the redistribute command must include the subnets keyword to redistribute classless subnets. Without it, only classful networks are redistributed, which may cause many routes to be missing.

Answer

OSPF process 1 has a higher administrative distance than OSPF process 2.

Answer

The redistribute ospf 1 command under OSPF process 2 is missing the match internal keyword.

Answer

OSPF process 2 has a route map applied that is filtering all routes.

Question 4

A network engineer is troubleshooting a route redistribution issue between RIP and OSPF. Router R1 runs both RIP and OSPF, and redistributes RIP routes into OSPF. The engineer notices that RIP routes are not appearing in the OSPF database on neighboring routers. The show ip ospf database external command on a neighbor shows no external routes from R1. The redistribute rip command is configured under OSPF on R1. What is the most likely cause?

Accepted Answer

The redistribute rip command under OSPF is missing the subnets keyword.. When redistributing into OSPF, the subnets keyword is required to redistribute classless subnets. Without it, only classful networks are advertised, which may cause many routes to be missing.

Answer

RIP has a higher administrative distance than OSPF.

Answer

The OSPF process on R1 has a distribute-list blocking these routes.

Answer

The RIP process on R1 is not running.

Question 5

A network engineer is troubleshooting a route redistribution issue between EIGRP and BGP. Router R1 runs both EIGRP and BGP, and redistributes EIGRP routes into BGP. The engineer notices that some EIGRP routes are not appearing in the BGP table on R1. The show ip bgp command does not list these prefixes. The redistribute eigrp command is configured under BGP. What is the most likely cause?

Accepted Answer

The EIGRP routes are not present in the IP routing table on R1.. When redistributing into BGP, by default only classful networks are redistributed unless the subnets keyword is used. Additionally, BGP does not redistribute routes that are not in the routing table. However, a common cause is that the EIGRP routes are not in the global routing table due to administrative distance or other reasons.

Answer

The redistribute eigrp command under BGP is missing the subnets keyword.

Answer

BGP has a higher administrative distance than EIGRP.

Answer

The EIGRP process on R1 has a route filter blocking these routes.

Question 6

A network engineer is troubleshooting a route redistribution issue between OSPF and BGP. Router R1 runs both OSPF and BGP, and redistributes OSPF routes into BGP. The engineer notices that OSPF external routes are not appearing in the BGP table on R1. The show ip bgp command does not list these prefixes. The redistribute ospf 1 match external command is configured under BGP. What is the most likely cause?

Accepted Answer

The redistribute ospf 1 match external command under BGP is missing the subnets keyword.. When redistributing OSPF into BGP, the subnets keyword is required to redistribute classless subnets. Without it, only classful networks are redistributed, which may cause many routes to be missing.

Answer

OSPF has a higher administrative distance than BGP.

Answer

The OSPF process on R1 has a distribute-list blocking these routes.

Answer

BGP requires the network command to advertise routes, not redistribution.

Question 7

A network engineer is troubleshooting a route redistribution issue between EIGRP and OSPF. Routers R1 (EIGRP) and R2 (OSPF) are redistributing routes. The engineer notices that some EIGRP routes are appearing in the OSPF database on R2, but traffic to those destinations is not being forwarded correctly. The show ip route command on R2 shows the redistributed routes with a next-hop of 0.0.0.0. What is the most likely cause?

Accepted Answer

The redistribute eigrp command under OSPF is missing the subnets keyword.. When redistributing into OSPF, if the redistributed routes are not directly connected to the redistributing router, the next-hop may be set to 0.0.0.0 (self) if the subnets keyword is missing or if the route is not in the routing table. However, a common cause is that the redistribute command is missing the subnets keyword, causing classful behavior.

Answer

The OSPF process on R2 has a route map that is changing the next-hop.

Answer

EIGRP has a lower administrative distance than OSPF.

Answer

The EIGRP routes are not in the routing table on R2.

Question 8

A network engineer is troubleshooting a route redistribution issue between OSPF and EIGRP. Routers R1 (OSPF) and R2 (EIGRP) are redistributing routes. The engineer notices that some OSPF routes are appearing in the EIGRP topology table on R2, but traffic to those destinations is being dropped. The show ip route command on R2 shows the redistributed routes with a next-hop of the R1 interface, but the route is not installed in the routing table. What is the most likely cause?

Accepted Answer

The redistribute ospf command under EIGRP is missing the default-metric configuration.. When redistributing from OSPF into EIGRP, the redistributed routes may have a next-hop that is not reachable via EIGRP, causing the route to be not installed in the routing table. This is often due to the default-metric not being set, causing EIGRP to use an incorrect metric.

Answer

OSPF has a higher administrative distance than EIGRP.

Answer

The EIGRP process on R2 has a distribute-list blocking these routes.

Answer

The OSPF process on R1 has a route filter blocking these routes.

Question 9

A network engineer is troubleshooting a route redistribution issue between two EIGRP processes. Router R1 runs EIGRP AS 100 and EIGRP AS 200, and redistributes routes between them. The engineer notices that routes from EIGRP AS 100 are not appearing in the EIGRP topology table of AS 200 on R1. The redistribute eigrp 100 command is configured under EIGRP AS 200. What is the most likely cause?

Accepted Answer

The redistribute eigrp 100 command under EIGRP AS 200 is missing the metric specification.. When redistributing between EIGRP processes, the redistribute command must include the metric values (bandwidth, delay, reliability, load, MTU) or a default-metric must be configured. Without a metric, the redistributed routes are not accepted.

Answer

EIGRP AS 100 has a higher administrative distance than EIGRP AS 200.

Answer

The redistribute eigrp 100 command under EIGRP AS 200 is missing the subnets keyword.

Answer

EIGRP AS 200 has a route map that is filtering all routes.

Question 10

A network engineer runs the following command on Router R1:

R1# show ip eigrp topology 10.1.1.0/24
IP-EIGRP (AS 100): Topology entry for 10.1.1.0/24
  State: Passive, Originating reply status: 0
  Routing Descriptor Blocks:
  0.0.0.0 (Null0), from 0.0.0.0, Send flag: 0x0
      Composite metric is (2560000000/0), Route is Internal
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 100 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 0
  10.2.2.2 (GigabitEthernet0/1), from 10.2.2.2, Send flag: 0x0
      Composite metric is (2688000000/2560000000), Route is Internal
      Vector metric:
        Minimum bandwidth is 100000 Kbit
        Total delay is 200 microseconds
        Reliability is 255/255
        Load is 1/255
        Minimum MTU is 1500
        Hop count is 1

Based on this output, what is the problem?

Accepted Answer

A manual summary route is configured on R1 for 10.1.1.0/24, causing a local Null0 entry.. The output shows a Null0 entry with a metric of 2560000000/0, which is characteristic of a summary route. The problem is that an EIGRP summary route is being advertised, but the route is also learned from another neighbor (10.2.2.2) with a higher metric, indicating potential suboptimal routing or a missing 'no auto-summary' command.

Answer

The route 10.1.1.0/24 is redistributed from another protocol into EIGRP.

Answer

The route 10.1.1.0/24 is flapping between Passive and Active states.

Answer

The neighbor 10.2.2.2 is not reachable, so the route is installed via Null0.

Question 11

A network engineer runs the following command on Router R1:

R1# show ip ospf database external 10.1.1.0

OSPF Router with ID (1.1.1.1) (Process ID 1)

Type-5 AS External Link States (Area 0)

LS age: 120
  Options: (No TOS-capability, DC)
  LS Type: AS External Link
  Link State ID: 10.1.1.0 (External Network Number)
  Advertising Router: 2.2.2.2
  LS Seq Number: 80000001
  Checksum: 0x1234
  Length: 36
  Network Mask: /24
        Metric Type: 2 (Larger than any link state path)
        TOS: 0
        Metric: 20
        Forward Address: 0.0.0.0
        External Route Tag: 100

Based on this output, which statement is correct?

Accepted Answer

The route 10.1.1.0/24 is redistributed into OSPF from another protocol with a route-map setting the tag to 100.. The output shows an OSPF Type-5 external LSA for 10.1.1.0/24 with Metric Type 2 and Metric 20. The default metric for redistributed routes in OSPF is 20 for Type 2. The External Route Tag of 100 indicates a redistribution tag, often used for filtering or route-maps.

Answer

The route 10.1.1.0/24 is an OSPF inter-area route from area 0.

Answer

The metric of 20 indicates the route is redistributed with a default metric of 20, which is correct for Type 1 external routes.

Answer

The forward address of 0.0.0.0 indicates that the next hop is the advertising router 2.2.2.2.

Question 12

A network engineer runs the following command on Router R1:

R1# show ip bgp 10.1.1.0/24
BGP routing table entry for 10.1.1.0/24, version 10
Paths: (1 available, best #1, table default)
  Advertised to update-groups:
     1
  Refresh Epoch 1
  Local
    10.2.2.2 from 10.2.2.2 (2.2.2.2)
      Origin IGP, metric 0, localpref 100, valid, external, best
      rx pathid: 0, tx pathid: 0x0
      Community: 100:200

Based on this output, what is the problem?

Accepted Answer

The route 10.1.1.0/24 is redistributed from an IGP into BGP, as indicated by the 'Local' path.. The output shows a BGP route with 'Local' as the path, meaning it was redistributed into BGP locally. The origin is IGP, and the community is 100:200. The route is valid and best. However, the 'Local' path indicates redistribution from an IGP into BGP, which is common in redistribution scenarios.

Answer

The route 10.1.1.0/24 is learned via an eBGP session and has a local preference of 100.

Answer

The community 100:200 is automatically assigned by BGP for all redistributed routes.

Answer

The route is not being advertised to any peers because it is not marked as best.

Question 13

A network engineer runs the following command on Router R1:

R1# show route-map REDISTRIBUTE
route-map REDISTRIBUTE, permit, sequence 10
  Match clauses:
    ip address prefix-list EIGRP_ROUTES
  Set clauses:
    metric 100
    metric-type type-1
    tag 200
  Policy routing matches: 0 packets, 0 bytes

route-map REDISTRIBUTE, deny, sequence 20
  Match clauses:
    ip address prefix-list DENY_ALL
  Set clauses:
  Policy routing matches: 0 packets, 0 bytes

Based on this output, what is the problem?

Accepted Answer

The route-map has a deny sequence that may block all routes if prefix-list DENY_ALL is configured to permit all.. The route-map has a deny sequence 20 that matches prefix-list DENY_ALL. If DENY_ALL is configured to permit all (e.g., permit 0.0.0.0/0 le 32), then all routes will be denied after sequence 10, effectively blocking redistribution. The problem is that the deny sequence may unintentionally block routes that should be redistributed.

Answer

The route-map will redistribute all routes that match prefix-list EIGRP_ROUTES with metric 100 and type-1.

Answer

The route-map will only redistribute routes with tag 200.

Answer

The route-map is not applied to any redistribution command, so it has no effect.

Question 14

A network engineer runs the following command on Router R1:

R1# show ip route 10.1.1.0
Routing entry for 10.1.1.0/24
  Known via "eigrp 100", distance 170, metric 2560000
  Redistributing via eigrp 100
  Advertised by eigrp 100 (self originated)
  Last update from 10.2.2.2 on GigabitEthernet0/1, 00:00:10 ago
  Routing Descriptor Blocks:
  * 10.2.2.2, from 10.2.2.2, 00:00:10 ago, via GigabitEthernet0/1
      Route metric is 2560000, traffic share count is 1
      Total delay is 100 microseconds, minimum bandwidth is 100000 Kbit
      Reliability 255/255, minimum MTU 1500
      Loading 1/255, Hops 1

Based on this output, what is the problem?

Accepted Answer

The route is redistributed into EIGRP from another protocol, as indicated by the distance of 170 and the 'self originated' message.. The output shows a route learned via EIGRP with an administrative distance of 170, which is the default for external EIGRP routes. The route is marked as 'Redistributing via eigrp 100' and 'Advertised by eigrp 100 (self originated)', indicating that this route was redistributed into EIGRP from another protocol. The problem is that the route is both learned and redistributed by the same router, which could cause a routing loop if not filtered.

Answer

The route 10.1.1.0/24 is an internal EIGRP route because the administrative distance is 90.

Answer

The route is learned from a neighbor with a metric of 2560000, which is the default for redistributed routes.

Answer

The route is not being advertised to any EIGRP neighbors because it is marked as 'self originated'.

Question 15

A network engineer runs the following command on Router R1:

R1# show ip ospf interface GigabitEthernet0/1
GigabitEthernet0/1 is up, line protocol is up
  Internet Address 10.1.1.1/24, Area 0
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
  Transmit Delay is 1 sec, State DR, Priority 1
  Designated Router (ID) 1.1.1.1, Interface address 10.1.1.1
  Backup Designated router (ID) 2.2.2.2, Interface address 10.1.1.2
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:03
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/1, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 25
  Last flood scan time is 0 msec, maximum is 4 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 2.2.2.2  (Backup Designated Router)
  Suppress hello for 0 neighbor(s)

Based on this output, what is the problem?

Accepted Answer

The output shows no external routes are being redistributed, but this is a normal interface status.. The output shows R1 is the Designated Router (DR) on a broadcast network. The neighbor count is 1, which is normal. However, the problem might be that redistribution is not happening because the interface is in area 0, but no external routes are seen. The output itself does not show a direct problem; it is a normal OSPF interface state. The question likely expects the candidate to note that the interface is functioning correctly, but the context of redistribution might imply that redistribution is configured but not working due to other issues.

Answer

The router is the DR, which is normal, but the neighbor count of 1 indicates only one OSPF neighbor is present.

Answer

The interface is in area 0, but redistribution of external routes requires a route-map to set the metric.

Answer

The router ID is 1.1.1.1, which is not reachable from other routers.