QuestionQ220

Unicast Routing

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Refer to the exhibit. A network engineer installed a new router (Router 3) at the regional hub, which runs MPLS services for scalability. Router 3 connects 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 is configured for OSPF Area 2 and advertises the four connected networks. The engineer observes that the same networks appear as interarea summary routes and are flooded into each area at the area borders. Which action resolves the issue?

  • A Under the OSPF configuration on Router 2, add area 2 range 10.44.4.0 255.255.252.0.
  • B On Router 3, configure an access list to filter the networks.
  • C Under the OSPF configuration on Router 3, add area 2 range 10.44.4.0 255.255.252.0.
  • D On Router 2, configure a route map to filter the networks.
Explanation

Router 2 is the ABR between Area 2 and Area 0. Configuring an Area 2 range of 10.44.4.0 255.255.252.0 on that ABR summarizes the four contiguous /24 networks as one 10.44.4.0/22 Type 3 interarea summary route when advertised outside Area 2. OSPF area-range summarization is performed at an ABR.

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