hardMultiple Choice
CCNP Practice Question: Runs the following command on Router R1: R1# show…
A network engineer runs the following command on Router R1:
R1# show ip pim neighbor
PIM Neighbor Table
Neighbor Address Interface Uptime Expires Mode 10.0.0.2 GigabitEthernet0/0 00:10:00 00:01:30 Dense 10.0.0.3 GigabitEthernet0/1 00:20:00 00:01:20 Sparse
Based on this output, what can be concluded?
⚠ Common exam trap
Cisco often tests the ability to read the 'Mode' column in the 'show ip pim neighbor' output, where candidates mistakenly assume all neighbors share the same mode or that the mode column indicates the router's global PIM mode rather than per-interface configuration.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The router is configured with mixed PIM modes on different interfaces
The output shows that interface GigabitEthernet0/0 has a PIM neighbor in Dense mode, while GigabitEthernet0/1 has a neighbor in Sparse mode. This indicates that Router R1 is configured with different PIM modes on different interfaces, which is known as mixed PIM mode. Therefore, option B is correct.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
All PIM neighbors are operating in sparse mode
Why it's wrong here
The assertion that all PIM neighbors are in sparse mode is incorrect because the output explicitly identifies neighbor 10.0.0.2 as operating in Dense mode. In PIM, each interface's mode determines how neighbor relationships are formed, and mixed modes produce neighbors in different states. Since one neighbor is Dense and the other is Sparse, the claim of uniform sparse mode is contradictory to the observed data.
- ✓
The router is configured with mixed PIM modes on different interfaces
Why this is correct
The router is correctly identified as having mixed PIM modes on different interfaces because the neighbor table shows one neighbor in Dense mode and another in Sparse mode. This indicates that the router's interfaces are configured with different PIM modes, as PIM mode is a per-interface setting. Such a configuration is valid but can lead to suboptimal multicast behavior if not carefully planned, as dense mode floods traffic while sparse mode requires explicit joins.
- ✗
The router is using PIM version 2 exclusively
Why it's wrong here
The claim that the router uses only PIM version 2 is unsupported because the provided output contains no information about the PIM version. PIM version and PIM mode are independent attributes; an interface can run version 2 in either dense or sparse mode. Without explicit version fields in the output, asserting exclusively version 2 is merely speculative and not a conclusion that can be drawn from the given data.
- ✗
The neighbor 10.0.0.3 is not a valid PIM neighbor
Why it's wrong here
The statement that neighbor 10.0.0.3 is invalid is wrong because the neighbor table lists it with both an uptime and an expiration timer, which are only maintained for recognized and active PIM neighbors. Valid neighbors must have exchanged PIM hello messages and be reachable; the presence of timers confirms this state. An invalid neighbor would either be absent from the table or marked as inactive, neither of which applies here.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.