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Device Management →mediumMultiple ChoiceObjective-mapped

BGP Neighbor Idle State Troubleshooting

This 300-410 practice question tests your understanding of device management. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.

A network engineer runs the following command on Router R1:

R1# show bgp ipv4 unicast summary

BGP router identifier 192.168.0.1, local AS number 65001 BGP table version is 10, main routing table version 10

Neighbor        V           AS MsgRcvd MsgSent   TblVer  InQ OutQ Up/Down  State/PfxRcd
192.168.1.2     4        65002    1002    1000       10    0    0 00:15:30        5
192.168.2.2     4        65003    1005    1003       10    0    0 00:14:20        3
10.10.10.2      4        65004       0       0        0    0    0 00:00:05 Idle

Based on this output, what is the problem with neighbor 10.10.10.2?

Quick Answer

The answer is that neighbor 10.10.10.2 is stuck in the Idle state because the BGP session has not been established, likely due to a misconfiguration or a reachability issue. In BGP, the Idle state is the initial state of the neighbor finite state machine, and a router enters this state when it lacks a valid TCP connection to the peer; the zero message counts and the brief uptime of only five seconds confirm that no TCP handshake or BGP OPEN messages have been exchanged. This scenario directly tests your ability to interpret the `show bgp ipv4 unicast summary` output for the Cisco CCNP ENARSI 300-410 exam, where a common trap is confusing Idle with Active—remember that Idle means the router is not even attempting to connect, often pointing to a missing `neighbor` statement, an incorrect remote AS number, or an IP address that is unreachable. A quick memory tip: “Idle means idle—no TCP, no try.”

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 BGP session is not established; possible misconfiguration or reachability issue.

The output shows that neighbor 10.10.10.2 is in the Idle state with zero messages sent or received, indicating the BGP session has never been established. This typically results from a misconfiguration (e.g., wrong neighbor IP, incorrect AS number, missing update-source) or a Layer 3 reachability issue preventing the TCP connection on port 179.

Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Answer analysis

Option-by-option breakdown

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

  • ✗

    The neighbor is administratively shut down.

    Why it's wrong here

    Idle state can result from many issues, but not specifically admin shutdown without further evidence.

  • ✓

    The BGP session is not established; possible misconfiguration or reachability issue.

    Why this is correct

    Idle state with no messages indicates the session is down.

    Related concept

    Read the scenario before looking for a memorised answer.

  • ✗

    The neighbor is in the process of establishing the session.

    Why it's wrong here

    Idle is not a transitional state; it indicates a failure.

  • ✗

    The neighbor has sent all its prefixes and is waiting for updates.

    Why it's wrong here

    Idle state means no session exists.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between Idle (no session attempt) and Active (session attempt in progress), tricking candidates into thinking Idle means 'waiting' rather than 'not started'.

Detailed technical explanation

How to think about this question

BGP uses TCP port 179 for session establishment; the Idle state is the initial state where BGP refuses all inbound connections and does not initiate any. The router remains in Idle until a start event (e.g., 'neighbor' command) triggers a transition to Connect, but if the TCP connection fails repeatedly due to unreachability or misconfiguration, the session may cycle or stay Idle. In real-world scenarios, this often occurs when an eBGP multihop configuration is missing or an ACL blocks TCP/179.

KKey Concepts to Remember

  • Read the scenario before looking for a memorised answer.
  • Find the constraint that changes the correct option.
  • Eliminate answers that are true in general but not in this case.

TExam Day Tips

  • Watch for words such as best, first, most likely and least administrative effort.
  • Review why wrong options are wrong, not only why the correct option is correct.

Key takeaway

Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.

Real-world example

How this comes up in practice

A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.

Visual reference

Client Server SYN (seq=100) SYN-ACK (seq=200, ack=101) ACK (ack=201) Connection established — data transfer begins

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this 300-410 question test?

Device Management — This question tests Device Management — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: The BGP session is not established; possible misconfiguration or reachability issue. — The output shows that neighbor 10.10.10.2 is in the Idle state with zero messages sent or received, indicating the BGP session has never been established. This typically results from a misconfiguration (e.g., wrong neighbor IP, incorrect AS number, missing update-source) or a Layer 3 reachability issue preventing the TCP connection on port 179.

What should I do if I get this 300-410 question wrong?

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

What is the key concept behind this question?

Read the scenario before looking for a memorised answer.

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Last reviewed: Jul 4, 2026

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This 300-410 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 300-410 exam.