CCNP Virtualization Practice Question
A network engineer is configuring VXLAN on a Cisco Nexus 9000 switch. The engineer wants to ensure that the VXLAN tunnel interface uses the loopback 0 interface as the source for all VXLAN traffic. Which command should be entered under the NVE interface configuration?
⚠ Common exam trap
Watch out — candidates often confuse the command syntax for VXLAN with that of traditional GRE tunnels, leading to the use of 'tunnel source' instead of the correct 'source-interface'.
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
✓
source-interface loopback0
The correct command to set the source interface for VXLAN tunnels under the NVE interface is 'source-interface loopback0'. This ensures that the VTEP IP address is derived from a stable loopback interface, which is a best practice for VXLAN deployments. The other options are either invalid or apply to different technologies.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
tunnel source loopback0
Why it's wrong here
This command is used for traditional GRE tunnels, not for VXLAN on Nexus 9000. VXLAN uses the NVE interface and the 'source-interface' command. The 'tunnel source' command would not be recognized under the NVE configuration and is not the correct method for VXLAN.
- ✓
source-interface loopback0
Why this is correct
This command correctly specifies the loopback 0 interface as the source for VXLAN tunnel traffic. It ensures that the VTEP IP address is derived from a stable, always-up interface, which is a best practice for VXLAN deployments. The loopback interface provides redundancy and avoids disruption if a physical interface goes down.
- ✗
vxlan source-interface loopback0
Why it's wrong here
This command is not valid under the NVE interface. The correct syntax is 'source-interface loopback0' without the 'vxlan' prefix. The 'vxlan' keyword is not used in this context; it is implied by the NVE configuration mode. Using this command would result in an error.
- ✗
interface loopback0
Why it's wrong here
This command is used to enter the loopback interface configuration mode, not to set it as the source for VXLAN. Under the NVE interface, you must use the 'source-interface' keyword to designate the source. Simply referencing the loopback interface does not configure the VXLAN tunnel source.
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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.