CCNP Virtualization Practice Question
A network engineer is configuring a VRF on a Cisco IOS-XE router to isolate a customer's traffic. The engineer creates VRF CUST_A, assigns the customer-facing interface to it, and runs the show ip route vrf CUST_A command, which returns no routes. The interface is up and the customer router is reachable. What is the most likely cause?
⚠ Common exam trap
The trap here is assuming a VRF needs a route distinguisher and route target to hold local routes, when those are only needed for MPLS L3VPN signaling.
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 interface was placed in the VRF, but no IP address or routing protocol was configured on that interface within the VRF.
A VRF routing table is populated by connected routes from interfaces that both belong to the VRF and have IP addresses, plus any static routes or dynamic routing configured inside the VRF address family. If the interface was moved into the VRF but never addressed, or if no routing protocol or static route was configured within the VRF, the table stays empty. Verifying the interface address and the VRF's routing configuration explains the symptom.
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 ip vrf forwarding command must be applied to the VRF definition rather than to the interface.
Why it's wrong here
The ip vrf forwarding command is applied to the interface to associate it with a VRF; it is not applied to the VRF definition itself. The VRF definition is created with the vrf definition command and configured with rd and address-family settings. Applying forwarding to the definition is not a valid configuration step and would not add routes to the VRF.
- ✗
The VRF was created but no route distinguisher or route target was configured, which is required for any VRF to install routes.
Why it's wrong here
A route distinguisher and route targets are required only when the VRF participates in MPLS Layer 3 VPN or similar BGP-based VPN signaling. A local VRF used purely for interface-based traffic isolation on a single router does not need a route distinguisher or route target to install connected and static routes, so this is not the cause of the empty table.
- ✗
The global routing table must be cleared with the clear ip route * command before VRF routes will appear.
Why it's wrong here
Clearing the global routing table does not populate a VRF table and would disrupt production traffic on the router. VRF route installation depends on the configuration inside the VRF, not on the state of the global table, so this action would not resolve the empty CUST_A table and could cause an outage.
- ✓
The interface was placed in the VRF, but no IP address or routing protocol was configured on that interface within the VRF.
Why this is correct
An interface assigned to a VRF contributes its connected route to that VRF's table only if it has an IP address. If the interface has no address, or if no static route or routing protocol is configured inside the VRF address family, the VRF routing table will be empty. This matches the symptom of show ip route vrf CUST_A returning no routes.
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.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Cisco exam blueprint
This 350-401 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 350-401 exam.