300-510 · Question #161
Refer to the exhibit. A network engineer installed a new router (Router 3) at the regional hub running MPLS services for scalability. Router 3 is connected to the 10.44.4.0/24, 10.44.5.0/24…
The correct answer is D. Under the OSPF configuration on router 2, add area 2 range 10.44.4.0 255.255.252.0. OSPF inter-area summarization (route aggregation) must be configured on the Area Border Router (ABR), not on an internal router. Router 3 is an internal router in Area 2 - it cannot perform inter-area summarization regardless of any range command configured locally. Router 2 is…
Question
Refer to the exhibit. A network engineer installed a new router (Router 3) at the regional hub running MPLS services for scalability. Router 3 is connected to the 10.44.4.0/24, 10.44.5.0/24, 10.44.6.0/24, and 10.44.7.0/24 subnets. The new router has been configured for OSPF Area 2, and it is advertising the four connected networks. The engineer noticed that the same networks are listed as interarea summary routes, and they are being flooded into each area on the area borders. Which action resolves the issue?
Exhibit
Options
- AOn router 3, configure an access list to filter the networks.
- BOn router 2, configure a route map to filter the networks.
- CUnder the OSPF configuration on router 3, add area 2 range 10.44.4.0 255.255.252.0.
- DUnder the OSPF configuration on router 2, add area 2 range 10.44.4.0 255.255.252.0.
How the community answered
(53 responses)- A19% (10)
- B6% (3)
- C4% (2)
- D72% (38)
Explanation
OSPF inter-area summarization (route aggregation) must be configured on the Area Border Router (ABR), not on an internal router. Router 3 is an internal router in Area 2 - it cannot perform inter-area summarization regardless of any range command configured locally. Router 2 is the ABR sitting between Area 2 and Area 0 (the backbone). By configuring 'area 2 range 10.44.4.0 255.255.252.0' on Router 2, the ABR will advertise a single summary LSA (10.44.4.0/22) into Area 0 instead of four separate Type 3 LSAs, stopping the individual /24 routes from flooding into other areas. The /22 mask (255.255.252.0) correctly encompasses all four /24 subnets (10.44.4.0 through 10.44.7.0).
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