350-401 Virtualization Practice Question
A network engineer is configuring a Cisco CSR 1000v router to support a virtual routing and forwarding (VRF) instance for a customer. The engineer wants to enable OSPFv2 within the VRF and ensure that OSPF routes are installed in the VRF's routing table. Which command is required to start the OSPF process for the VRF?
⚠ Common exam trap
The trap here is mixing up IOS-XE and NX-OS syntax, or incorrectly placing the VRF parameter on a separate line instead of on the router ospf command itself.
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
✓
router ospf 1 vrf CUSTOMER
The correct command to enable OSPFv2 in a VRF on Cisco IOS-XE is 'router ospf <process-id> vrf <vrf-name>'. This associates the OSPF process with the specified VRF, allowing it to run in that VRF's routing context. The other options either use incorrect syntax or are appropriate for different platforms or protocols.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
router ospf 1 vrf CUSTOMER
Why this is correct
The command 'router ospf 1 vrf CUSTOMER' starts an OSPF process with process ID 1 and associates it with the VRF named CUSTOMER. This is the correct syntax to enable OSPF within a specific VRF on Cisco IOS-XE. Once configured, OSPF will run in the context of that VRF, and routes will be installed in the VRF's routing table.
- ✗
ip router ospf 1 vrf CUSTOMER
Why it's wrong here
This command is not valid for enabling OSPF in a VRF on Cisco IOS-XE. 'ip router ospf' is used in Cisco NX-OS, not IOS-XE. On IOS-XE, the correct command is 'router ospf <process-id> vrf <vrf-name>'. Using this command would result in an error and OSPF would not be enabled for the VRF.
- ✗
router ospf 1 address-family ipv4 vrf CUSTOMER
Why it's wrong here
This command sequence is used for multi-protocol BGP (MP-BGP) or OSPFv3 address families, not for OSPFv2 in a VRF. OSPFv2 does not use address families in this manner on IOS-XE. The correct way to enable OSPFv2 in a VRF is to specify the VRF on the router ospf command line. This option would not correctly enable OSPF for the VRF.
- ✗
router ospf 1 vrf CUSTOMER
Why it's wrong here
This syntax is incorrect. The VRF must be specified on the same line as the 'router ospf' command, not as a subcommand. Placing 'vrf CUSTOMER' on a separate line under the router ospf configuration would result in a syntax error or be interpreted as an unrecognized command, and OSPF would not be associated with the VRF.
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.
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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.