hardMultiple ChoiceObjective-mapped
300-410 Practice Question: An engineer is troubleshooting an MPLS L3VPN…
An engineer is troubleshooting an MPLS L3VPN where CE1 (10.1.1.0/24) cannot reach CE2 (10.2.2.0/24). The PE routers have MP-BGP peering and the VRF is configured with route-target import 100:100. On PE1, the show ip bgp vpnv4 vrf CUSTOMER command shows the route for 10.2.2.0/24 with a next-hop of 192.168.1.2 (the PE2 loopback), but the show ip route vrf CUSTOMER command does not have this route. The show mpls forwarding-table on PE1 does not show a label for 192.168.1.2. What is the most likely cause?
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
✓
LDP is not enabled on the core-facing interfaces of PE1 or the P routers.
The VPNv4 route is received but not installed in the VRF routing table because the recursive lookup fails: the next-hop (PE2 loopback) is not reachable via LDP. Without an LDP label for the BGP next-hop, the route cannot be installed.
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 VRF route-target import is missing on PE2.
Why it's wrong here
Incorrect because the route is received on PE1, so import is working.
- ✓
LDP is not enabled on the core-facing interfaces of PE1 or the P routers.
Why this is correct
Correct: Without LDP, there is no label for the BGP next-hop, preventing route installation.
- ✗
The MP-BGP session is not using the loopback interface.
Why it's wrong here
Incorrect because the route shows a next-hop of the loopback, indicating the session is using it.
- ✗
The VRF on PE1 has the wrong route-target export.
Why it's wrong here
Incorrect because the issue is with route installation, not export.
Go deeper
Related to this question
Learn chapter
OSPF Route Summarization and Filtering
Key term
MP-BGP for VPN
MP-BGP for VPN is an extension of the Border Gateway Protocol that carries multiple types of network layer information to enable scalable, isolated virtual private networks over a shared provider infrastructure.
Key term
MPLS Label Distribution
MPLS Label Distribution is the process by which routers exchange labels that tell them how to forward packets across a network without looking at the IP address each time.
About these practice questions
This 300-410 question is part of Courseiva's 1,966-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.