Junos Enterprise Routing, 2nd Edition

Chapter Review Answers

1. Answer: D. Split horizon rules prevent a router from readvertising routing information back out the same interface it was learned from; poisoned reverse alters this behavior to permit such updates as long as they have an infinite metric.

2. Answer: C. You specify RIP-enabled interfaces by name and unit number, under the [edit protocols rip group <name> neighbor] hierarchy.

3. Answer: C. The show route advertising protocol <protocol> <neighbor> command is used to display the route the local router is sending out an interface to a neighbor for RIP/BGP, respectively. The receiving-protocol form of this command shows the routes being learned over an interface.

4. Answer: D. Only designated routers, which are elected only on multiaccess networks, generate Type 2 network summary LSAs. This LSA type is used to report the list of OSPF neighbors (including the DR itself) attached to the multiaccess segment.

5. Answer: C. A stub area with no-summaries does not receive summary LSAs from the backbone. It relies on an injected default route to reach interarea and AS external destinations.

6. Answer: D. All of the factors listed influence whether a given router can become the DR. Recall that DR election is not revertive. A router’s ID and priority come into play only during an active DR election.

7. Answer: D. The protocol with the numerically lowest preference (or administrative distance) is considered more “reliable” and is chosen as the source of the active route.

8. Answer: C. Your goal is to ...