hardMultiple Choice
CCNP Practice Question: Runs the following command on Router R4: R4# show…
A network engineer runs the following command on Router R4:
R4# show mpls ldp neighbor vrf CUSTOMER-C
Peer LDP Ident: 10.0.0.5:0; Local LDP Ident 10.0.0.4:0 TCP connection: 10.0.0.5.646 - 10.0.0.4.646 State: Oper; Msgs sent/rcvd: 500/500; Downstream Up time: 02:30:00 LDP discovery sources: GigabitEthernet0/0.300, Src IP addr: 10.0.1.2 hello sent/rcvd: 1000/1000 Addresses bound to peer LDP Ident:
10.0.1.2 10.0.2.2
Based on this output, what can be concluded?
⚠ Common exam trap
Cisco often tests the distinction between LDP (TCP port 646) and BGP (TCP port 179), and candidates may confuse the 'Oper' state with a BGP session or assume LDP uses port 179 by default.
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 operational with peer 10.0.0.5
The output shows 'State: Oper' and 'Up time: 02:30:00', which confirms the LDP session is fully operational. The peer LDP Ident is 10.0.0.5:0 and the local LDP Ident is 10.0.0.4:0, with a TCP connection established on port 646. This directly indicates that the LDP session with peer 10.0.0.5 is up and running.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
LDP is not configured for VRF CUSTOMER-C
Why it's wrong here
The output of 'show mpls ldp neighbor' indicates there is a neighbor, meaning LDP is configured and running for the VRF. A lack of configuration would produce no neighbor entries, not an operational session. So the statement is false because the presence of peer 10.0.0.5 with state Oper proves LDP is configured and exchanging label bindings.
- ✓
The LDP session is operational with peer 10.0.0.5
Why this is correct
The neighbor state 'Oper' confirms the LDP session is up and exchanging label mapping messages with the peer at 10.0.0.5. This is the only accurate conclusion among the choices. Operational implies the TCP connection on port 646 and the LDP initialization handshake have completed successfully.
- ✗
The LDP session is using TCP port 179
Why it's wrong here
BGP uses TCP port 179, while LDP specifically uses TCP port 646 for its session. The output shows an LDP neighbor, so it must be using port 646. Claiming port 179 confuses LDP with BGP and misidentifies the transport protocol.
- ✗
The peer is discovered via OSPF
Why it's wrong here
LDP peer discovery is performed by sending link-local hello messages on the interface (GigabitEthernet0/0.300), not through OSPF or any IGP. OSPF may be used for routing in the VRF, but it does not discover LDP neighbors. The hello mechanism establishes adjacency before TCP session can be initiated.
Visual reference
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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.