20+ practice questions focused on MPLS L3VPN — one of the most tested topics on the Cisco CCNP ENARSI 300-410 exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start MPLS L3VPN PracticeA network engineer is troubleshooting an MPLS L3VPN where CE1 (192.168.1.0/24) cannot reach CE2 (192.168.2.0/24). The PE routers are running OSPF with the CEs. On PE1, the VRF configuration includes route-target import and export 100:100. The show ip vrf detail command on PE1 shows the VRF is active, but the CE1 loopback is not present in the VRF routing table. The show ip route vrf CUSTOMER command on PE1 shows only directly connected interfaces. What is the most likely cause?
Explanation: The CE routes are not being learned via OSPF into the VRF because OSPF process is not associated with the VRF. Without the 'router ospf <pid> vrf <name>' command, OSPF runs in the global routing table and does not populate the VRF.
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?
Explanation: 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.
A network engineer is troubleshooting an MPLS L3VPN where CE1 (10.1.1.0/24) cannot reach CE2 (10.2.2.0/24). The PE routers are using OSPF with the CEs and MP-BGP between them. 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, and the show ip route vrf CUSTOMER command shows the route as well. However, traffic from CE1 to CE2 fails. The show ip cef vrf CUSTOMER 10.2.2.0 command on PE1 shows the next-hop as 192.168.1.2 but the output interface is 'no route'. What is the most likely cause?
Explanation: CEF has a next-hop but no output interface because the recursive routing table lookup for the BGP next-hop (192.168.1.2) fails. The IGP (OSPF or IS-IS) does not have a route to the PE2 loopback, so CEF cannot resolve the adjacency.
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, but the show ip route vrf CUSTOMER command does not have this route. The show ip bgp vpnv4 all 10.2.2.0/24 command on PE1 shows the route is received but not best. What is the most likely cause?
Explanation: The route is received but not marked as best, so it is not installed in the routing table. Common reasons include the route being suppressed due to a higher AD from another source or the next-hop being unreachable. In this scenario, the most likely cause is that the BGP next-hop is not reachable in the global routing table.
A network engineer is troubleshooting an MPLS L3VPN where CE1 (10.1.1.0/24) cannot reach CE2 (10.2.2.0/24). The PE routers are using eBGP with the CEs. 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, and the show ip route vrf CUSTOMER command shows the route. However, traffic from CE1 to CE2 fails. The show ip cef vrf CUSTOMER 10.2.2.0 command on PE1 shows the next-hop as 192.168.1.2 and the output interface as GigabitEthernet0/0. The show mpls forwarding-table 192.168.1.2 detail command on PE1 shows a label but the outgoing interface is 'aggregate'. What is the most likely cause?
Explanation: The label for the BGP next-hop is pointing to 'aggregate', which means the router is the egress LSR for that prefix. This occurs when the PE2 loopback is also configured on PE1, causing the router to think it is the destination. The traffic is then dropped or looped because the router tries to process the packet locally instead of forwarding it.
+15 more MPLS L3VPN questions available
Practice all MPLS L3VPN questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of MPLS L3VPN. This tells you whether you need a concept refresher or just practice.
2. Review every explanation
For each question — right or wrong — read the full explanation. Understanding why an answer is correct is more valuable than knowing the answer itself.
3. Focus on exam traps
MPLS L3VPN questions on the 300-410 frequently use trap wording. Look for subtle differences in answers that test your precision, not just general knowledge.
4. Reach 80% consistently
Do repeated sessions until you score 80%+ three times in a row. Then move to mixed-mode practice to test cross-topic recall under realistic conditions.
The exact number varies per candidate. MPLS L3VPN is tested as part of the Cisco CCNP ENARSI 300-410 blueprint. Practicing with targeted MPLS L3VPN questions ensures you can handle any format or difficulty that appears.
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Difficulty is subjective, but MPLS L3VPN is a high-priority exam concept tested in multiple ways — direct recall, scenario analysis, and command-output interpretation. Consistent practice is the best way to build confidence.
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