EIGRP diagnostic: Which command displays all feasible successor routes known to a router under EIGRP?
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Ashow ip routes *
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Bshow ip eigrp summary
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Cshow ip eigrp topology
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Dshow ip eigrp adjacencies
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Eshow ip protocols
Answer
Correct Answer: show ip eigrp topology
Explanation
Introduction / Context:Enhanced Interior Gateway Routing Protocol (EIGRP) maintains successor and feasible successor routes. The feasible successor acts as a backup path if the primary fails.
Given Data / Assumptions:
- Task: Identify command showing feasible successors
- Possible EIGRP monitoring commands are provided
Concept / Approach:The EIGRP topology table stores successors and feasible successors. Successor routes appear in the routing table, but feasible successors remain in the topology table until needed.
Step-by-Step Solution:
Check routing table: only shows active successors, not feasible ones.Check summary: shows neighbor counts and AS but not topology.Check adjacency: shows neighbor relationships, not routes.Correct command: show ip eigrp topology.Verification / Alternative check:Run the command in a lab; feasible successors are displayed with FD (feasible distance) metrics.
Why Other Options Are Wrong:
- show ip routes: Does not display backup routes.
- summary: High-level data only.
- adjacencies: Only neighbor info.
- protocols: Shows routing processes, not routes.
Common Pitfalls:Thinking feasible successors appear in the routing table—they do not until activated.
Final Answer:show ip eigrp topology