20+ practice questions focused on MPLS — one of the most tested topics on the ENCOR 350-401 exam. Each question includes a detailed explanation so you learn why the right answer is correct.
Start MPLS PracticeAn engineer is troubleshooting an MPLS VPN where CE1 (10.1.1.0/24) cannot reach CE2 (10.2.2.0/24). The PE routers are running OSPF with the CE routers. On PE1, the 'show ip route vrf CUSTOMER' output shows 10.2.2.0/24 as an OSPF route, but the prefix is not present in the global BGP table. What is the most likely cause?
Explanation: In MPLS L3VPN, CE routes must be redistributed into BGP (VPNv4) on the PE. If OSPF routes are present in the VRF but not in BGP, redistribution is missing. Option A correctly identifies this. Option B is wrong because OSPF is running; Option C is irrelevant; Option D would affect label allocation, not route advertisement.
A service provider uses MPLS L3VPN with OSPF as the PE-CE routing protocol. A customer reports that a new subnet added on CE1 is not reachable from CE2, even though the PE1 router has the route in its VRF and BGP table. The 'show ip bgp vpnv4 vrf CUSTOMER' on PE2 shows the prefix with a valid next-hop. What should the engineer check next?
Explanation: In MPLS L3VPN, even if BGP has the route, the packet forwarding requires a valid MPLS label for the next-hop. If LDP is not resolving the BGP next-hop, the route is not usable. Option A is correct. Option B is wrong because OSPF is fine; Option C is wrong because the route is in BGP; Option D is wrong because redistribution is already working.
An engineer is designing an MPLS L3VPN service for a customer that requires overlapping IP addresses between two sites. The customer uses OSPF as the PE-CE protocol. The engineer configures VRFs on the PE routers and assigns unique route distinguishers (RDs) and route targets (RTs). However, the customer reports that routes from one site are not being installed in the other site's VRF. What is the most likely cause?
Explanation: In MPLS L3VPN, route targets control the import/export of routes between VRFs. If the RTs are not configured correctly, routes will not be exchanged. Option A is correct. Option B is wrong because overlapping addresses are handled by VRFs; Option C is wrong because OSPF can handle overlapping addresses with proper configuration; Option D is wrong because RDs only make prefixes unique, they do not control route exchange.
A network engineer is configuring MPLS TE (Traffic Engineering) in an MPLS core to optimize bandwidth utilization. After enabling MPLS TE on all core routers and configuring tunnels, the engineer notices that traffic is not being rerouted when a link fails. The 'show mpls traffic-eng tunnels' shows the tunnels are up but not using the backup path. What is the most likely missing configuration?
Explanation: MPLS TE requires explicit backup path configuration, such as FRR (Fast Reroute) or backup tunnels, to provide protection. Without it, traffic will not be rerouted automatically. Option A is correct. Option B is wrong because LDP is not required for TE; Option C is wrong because RSVP is the signaling protocol, not the issue; Option D is wrong because link-state routing is fine.
An enterprise is implementing MPLS L3VPN to connect multiple branch offices. The PE routers are using eBGP to exchange VPNv4 routes. The engineer notices that some VPN routes are not being advertised to the remote PE. The 'show bgp vpnv4 unicast all' on the local PE shows the routes as valid but not best. What is the most likely reason?
Explanation: In BGP, only the best path is advertised to peers. If a route is valid but not best, it may be due to a higher local preference or other BGP path selection criteria. Option A is correct. Option B is wrong because the route is valid; Option C is wrong because the route is present; Option D is wrong because MED is not typically set by default.
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Practice all MPLS questions1. Baseline your knowledge
Start with 10 questions to gauge your current understanding of MPLS. 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 questions on the 350-401 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 is tested as part of the ENCOR 350-401 blueprint. Practicing with targeted MPLS questions ensures you can handle any format or difficulty that appears.
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Difficulty is subjective, but MPLS 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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