CCNP Practice Question: An enterprise network uses OSPF in the core and…

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✓

  Set appropriate administrative distance values for redistributed routes.

  Why this is correct

  Setting administrative distance (AD) for redistributed routes is essential because AD determines the trustworthiness of routing sources. When routes are redistributed between OSPF and EIGRP, their default AD values may cause a redistributed route (e.g., an EIGRP external route with AD 170) to be preferred over the original protocol's internal route, leading to routing loops or suboptimal paths. By explicitly setting AD values, you ensure that routes from the original protocol are always preferred, maintaining loop-free and predictable routing behavior.

• ✗

  Use route maps to filter all redistributed routes.

  Why it's wrong here

  Using route maps to filter all redistributed routes would indeed prevent any external routes from being injected into the other protocol, which could temporarily stop loops. However, this is a blunt instrument that completely breaks redistribution—the very purpose of the design—whereas the actual problem is not the existence of redistributed routes but the lack of proper route preference control. Filtering does not adjust AD or metrics, so even with selective filtering, loops can still occur when mutually redistributed routes with conflicting AD values exist.

• ✗

  Enable OSPF on all EIGRP interfaces.

  Why it's wrong here

  Enabling OSPF on all EIGRP interfaces does not prevent redistribution loops; instead, it creates a dual-protocol environment on every link, which introduces redundant routing information and forces routers to resolve conflicts via AD. This can actually increase the risk of loops because each protocol may independently forward traffic, and without careful AD tuning, packets can bounce between domains. Furthermore, it adds unnecessary protocol overhead and complexity, providing no mechanism to stop the specific route feedback loop caused by mutual redistribution.

• ✗

  Use a single routing protocol throughout the network.

  Why it's wrong here

  Using a single routing protocol throughout the network would completely avoid the need for redistribution, and thus would sidestep loops by design. However, this solution is not pragmatic in many enterprise environments where OSPF and EIGRP are already deployed, and the question scenario explicitly requires integrating these two protocols. The whole point of the design is to manage redistribution safely; abandoning one protocol is beyond the intended scope and may violate existing network requirements or migration constraints.