mediumMultiple Choice
350-401 Practice Question: Runs the following command on Router R1: R1# show…
A network engineer runs the following command on Router R1:
R1# show mpls ldp neighbor
Peer LDP Ident: 10.0.0.2:0; Local LDP Ident 10.0.0.1:0 TCP connection: 10.0.0.2.646 - 10.0.0.1.49231 State: Oper; Msgs sent/rcvd: 100/95; Downstream Up time: 01:23:45 LDP discovery sources: GigabitEthernet0/0, Src IP addr: 192.168.1.2 Addresses bound to peer LDP Ident:
10.0.0.2 192.168.1.2
Based on this output, what can be concluded?
⚠ Common exam trap
Cisco often tests the interpretation of the 'Up time' field, where candidates might overlook that the format includes seconds (HH:MM:SS) and incorrectly assume it only shows hours and minutes, leading them to select a partially correct but inaccurate option like D.
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 LDP session is using TCP port 646.
The output shows 'TCP connection: 10.0.0.2.646 - 10.0.0.1.49231', which indicates that the LDP session is using TCP port 646 on the peer side. This is the well-known port for Label Distribution Protocol (LDP), as defined in RFC 5036. The session state is 'Oper' (Operational), confirming the session is established and functioning correctly.
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 LDP session is not yet established.
Why it's wrong here
The state is shown as 'Oper', which is short for Operational. An LDP session in the Operational state has completed the TCP connection, initialization, and label exchange phases. If the session were not established, the state would instead appear as 'NonExistent', 'Initialized', or 'OpenRec', making this option factually incorrect.
- ✓
The LDP session is using TCP port 646.
Why this is correct
LDP uses TCP port 646 as its well-known transport port for reliable exchange of label binding messages. The output's TCP connection line explicitly lists port 646 for the remote endpoint, confirming that the session is running over the standard LDP TCP port. Had it been a non-default port, the configuration would have required an explicit 'port' statement under the MPLS LDP router configuration.
- ✗
The LDP neighbor is using a different router ID than 10.0.0.2.
Why it's wrong here
The neighbor's LDP identifier is shown as 'Peer LDP Ident: 10.0.0.2:0'. The format is Router-ID:Label-Space-ID, so the router ID portion is exactly 10.0.0.2, and the label space is 0. This directly contradicts the option's claim of a different router ID—the neighbor is using 10.0.0.2, not a different value.
- ✗
The LDP session has been up for 1 hour 23 minutes.
Why it's wrong here
The output's Uptime field is 01:23:45, which represents 1 hour, 23 minutes, and 45 seconds in HH:MM:SS format. The option states '1 hour 23 minutes,' which ignores the additional 45 seconds. Saying a session has been up for exactly 1 hour 23 minutes would require a value of 01:23:00, so the option is inaccurate.
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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.