The correct conclusion is that the LDP neighbor is reachable via GigabitEthernet0/0, as the output clearly shows the LDP session is operational with the state marked as “Oper” and the discovery source listing that specific interface. This interpretation hinges on understanding that the “LDP discovery sources” field reveals the directly connected interface and source IP address used to establish the neighbor relationship, while the “State: Oper” confirms the session is fully functional and exchanging label bindings. On the ENCOR 350-401 exam, this command tests your ability to verify MPLS LDP neighbor status and identify the underlying transport connection, often appearing in troubleshooting scenarios where a non-operational state like “INIT” or “DOWN” indicates a mismatch in router IDs or a firewall blocking TCP port 646. A common trap is confusing the peer LDP Ident (10.0.0.2:0) with the interface IP, but the discovery source always shows the actual Layer 3 adjacency. Remember the memory tip: “Oper means open, check the source for the path”—if the state is operational, the interface listed under discovery sources is where the labels are flowing.
CCNP SNMP and Syslog Practice Question
This 350-401 practice question tests your understanding of snmp and syslog. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 R5:
R5# show mpls ldp neighbor
Peer LDP Ident: 10.0.0.2:0, Local LDP Ident: 10.0.0.5:0
TCP connection: 10.0.0.2.646 - 10.0.0.5.646
State: Oper; Msgs sent/rcvd: 123/120; Downstream
Up time: 01:23:45
LDP discovery sources:
GigabitEthernet0/0, Src IP addr: 10.0.1.2
Addresses bound to peer LDP Ident:
The LDP session is down because the state is 'Oper'.
Why wrong: 'Oper' means operational, not down.
B
The LDP neighbor is reachable via GigabitEthernet0/0.
The LDP discovery sources show GigabitEthernet0/0 with source IP 10.0.1.2, indicating the neighbor is reachable through that interface.
C
The local LDP identifier is 10.0.0.2:0.
Why wrong: The local LDP Ident is 10.0.0.5:0, as shown in the first line. The peer LDP Ident is 10.0.0.2:0.
D
The LDP session has been up for 1 hour 23 minutes 45 seconds.
Why wrong: The up time is 01:23:45, which is 1 hour, 23 minutes, and 45 seconds. This is true, but not the best conclusion; the question asks for what can be concluded from the output, and the interface information is more specific.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The LDP neighbor is reachable via GigabitEthernet0/0.
The output shows an LDP neighbor with peer LDP identifier 10.0.0.2:0. The state is 'Oper' (operational). The discovery source is GigabitEthernet0/0 with source IP 10.0.1.2. The peer's addresses include 10.0.0.2, 10.0.1.2, and 192.168.1.1. The key conclusion is that the LDP session is established and operational.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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 down because the state is 'Oper'.
Why it's wrong here
'Oper' means operational, not down.
✓
The LDP neighbor is reachable via GigabitEthernet0/0.
Why this is correct
The LDP discovery sources show GigabitEthernet0/0 with source IP 10.0.1.2, indicating the neighbor is reachable through that interface.
The local LDP Ident is 10.0.0.5:0, as shown in the first line. The peer LDP Ident is 10.0.0.2:0.
✗
The LDP session has been up for 1 hour 23 minutes 45 seconds.
Why it's wrong here
The up time is 01:23:45, which is 1 hour, 23 minutes, and 45 seconds. This is true, but not the best conclusion; the question asks for what can be concluded from the output, and the interface information is more specific.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Trap categories for this question
Command / output trap
The local LDP Ident is 10.0.0.5:0, as shown in the first line. The peer LDP Ident is 10.0.0.2:0.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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.
What to study next
Got this wrong? Here's your next step.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-401 OSPF questions on adjacency and route selection.
SNMP and Syslog — This question tests SNMP and Syslog — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The LDP neighbor is reachable via GigabitEthernet0/0. — The output shows an LDP neighbor with peer LDP identifier 10.0.0.2:0. The state is 'Oper' (operational). The discovery source is GigabitEthernet0/0 with source IP 10.0.1.2. The peer's addresses include 10.0.0.2, 10.0.1.2, and 192.168.1.1. The key conclusion is that the LDP session is established and operational.
What should I do if I get this 350-401 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 350-401 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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