hardMultiple ChoiceObjective-mapped
300-410 Two VRFs on router R1: VRF A and VRF B Practice Question
Two VRFs on router R1: VRF A and VRF B. R1 has:
ip vrf A
rd 100:1 route-target export 100:1 route-target import 100:2
ip vrf B
rd 100:2 route-target export 100:2 route-target import 100:1 R1 shows:
R1# show ip route vrf A B 10.1.1.0/24 [200/0] via 10.2.2.2, 00:00:10 R1# show ip route vrf B B 10.1.1.0/24 [200/0] via 10.2.2.2, 00:00:10 Router R2 (in VRF A) can ping 10.1.1.1, but router R3 (in VRF B) cannot. What is the root 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
✓
The next hop 10.2.2.2 is not reachable from VRF B due to missing interface in VRF B.
The route targets are misconfigured for route leaking. VRF A exports with RT 100:1 and imports RT 100:2. VRF B exports with RT 100:2 and imports RT 100:1. This creates a two-way leak, but the route 10.1.1.0/24 is learned via BGP from R2. If R2 is in VRF A, the route is exported with RT 100:1. VRF B imports RT 100:1, so VRF B should have the route. However, the issue might be that the route is not being advertised to R3 due to BGP next-hop resolution or VRF interface issues. The output shows both VRFs have the route, so the problem is likely that R3 cannot reach the next hop 10.2.2.2 because it is in a different VRF or the interface is not in VRF B. The root cause is that the next hop is not reachable from VRF B.
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 next hop 10.2.2.2 is not reachable from VRF B due to missing interface in VRF B.
Why this is correct
The route is present, but the next hop is not in VRF B, so the route is not usable.
- ✗
The route targets are reversed, causing VRF B to not import the route.
Why it's wrong here
VRF B imports RT 100:1, which matches VRF A's export.
- ✗
BGP is not configured to advertise VPNv4 routes.
Why it's wrong here
The routes are present in both VRFs, so BGP is working.
- ✗
R3 has a firewall blocking ICMP.
Why it's wrong here
The issue is routing, not firewall.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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