hardMultiple ChoiceObjective-mapped
300-410 VRF-Lite Practice Question
A network engineer is troubleshooting reachability issues in a VRF-lite environment. R1 has the following configuration: ip vrf BLUE rd 100:1 route-target export 100:1 route-target import 100:1. R2 has: ip vrf BLUE rd 100:2 route-target export 100:2 route-target import 100:2. Both routers are connected via a link in the global routing table and are running OSPF in the VRF. R1 shows: 'show ip route vrf BLUE' has a route to 10.1.1.0/24 via OSPF, but R2 shows: 'show ip route vrf BLUE' does not have this route. What is the root cause?
⚠ Common exam trap
Candidates often confuse VRF-lite with MPLS L3VPN and assume route-target mismatch prevents route exchange, but in VRF-lite, OSPF over a link in the global table cannot form an adjacency within the VRF.
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 link between R1 and R2 is not in the VRF, so OSPF cannot form adjacency.
In VRF-lite, OSPF adjacency requires the link to be in the VRF context. The configuration shows both routers have OSPF in the VRF, but the connecting link is in the global routing table, not in VRF BLUE. Therefore, OSPF cannot form an adjacency over that link, and routes learned via OSPF within the VRF on R1 are not propagated to R2. Route-target import/export is used for MP-BGP VPNv4 route distribution, not for OSPF in VRF-lite. The correct fix is to put the link in the VRF (e.g., using 'ip vrf forwarding BLUE' on the interface).
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 route-target export on R1 (100:1) does not match the route-target import on R2 (100:2), so R2 does not import routes from R1.
Why it's wrong here
Incorrect. Route-target mismatch prevents MP-BGP route exchange in MPLS VPNs, but VRF-lite OSPF does not use route-targets for route propagation within the VRF.
- ✗
The OSPF process on R1 is not configured with the 'vrf BLUE' keyword.
Why it's wrong here
Incorrect. The 'vrf BLUE' keyword under router ospf is correctly implied; the issue is that the interface connecting the routers is not in the VRF.
- ✓
The link between R1 and R2 is not in the VRF, so OSPF cannot form adjacency.
Why this is correct
Correct. The link between R1 and R2 is not part of VRF BLUE, so OSPF cannot form an adjacency in that VRF, preventing route learning.
- ✗
The route 10.1.1.0/24 is being filtered by a distribute-list in OSPF.
Why it's wrong here
Incorrect. There is no indication of a distribute-list; the root cause is the missing VRF interface assignment, not filtering.
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
Introduction to ENARSI Exam and Network Fundamentals
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 Layer 3 VPN
A technology that uses Multiprotocol Label Switching to create secure, scalable virtual private networks that connect multiple sites at the network layer, where the service provider manages routing between customer sites.
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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.