RIP Metric of 16 — What Does debug ip rip Reveal? You enable debug ip rip and see network 172.16.10.0 being advertised to your router with metric 16. What does a RIP metric of 16 indicate for that route?

Difficulty: Easy

Correct Answer: The route is inaccessible.

Explanation:


Introduction / Context:
RIP uses hop count as its metric. The protocol defines a maximum of 15 hops; anything beyond that is considered unreachable to prevent routing loops from persisting indefinitely.


Given Data / Assumptions:

  • Protocol is RIP (v1 or v2).
  • Metric scale: 1–15 reachable, 16 = infinite (unreachable).
  • debug ip rip shows incoming updates and their metrics.


Concept / Approach:
A metric of 16 in RIP is the protocol’s representation of infinity. It marks a destination as unreachable, often used in route poisoning to explicitly withdraw a route. This avoids transient loops by ensuring all routers quickly treat the network as down until a valid advertisement appears.


Step-by-Step Solution:
Observe metric 16 in debug output.Map 16 → “infinite” in RIP metric space.Interpret as an unreachable/poisoned route.Expect neighbors to remove or de-preference the route accordingly.


Verification / Alternative check:
Check the routing table (show ip route). You should not see a usable path for 172.16.10.0 from that source; if present, it may be via another neighbor at a metric between 1 and 15.


Why Other Options Are Wrong:

  • A: 16 hops is beyond RIP’s maximum; the route would be considered unreachable.
  • B: Delay units are not used by RIP (that is an IGRP/EIGRP concept).
  • D: “Messages per second” is unrelated to the metric.
  • E: Summarization length is unrelated to a metric value of 16.


Common Pitfalls:
Confusing RIP’s metric of 16 with a legitimate distance; it is a sentinel for infinity only in RIP.


Final Answer:
The route is inaccessible.

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