- A
Connect a physical cable between two ports on the NFVIS host.
Why wrong: Incorrect because VNFs are virtual; a physical cable is not used for inter-VNF communication on the same host.
- B
Create a new bridge that connects both VNFs, or use a virtual switch to route between the bridges.
Correct because placing both VNFs on the same bridge allows Layer 2 communication; alternatively, a virtual router can route between bridges.
- C
Configure VLAN tagging on both VNFs with the same VLAN ID.
Why wrong: Incorrect because VLAN tagging alone does not connect different bridges; the bridges must be linked.
- D
Add a static route on each VNF pointing to the other VNF's IP address.
Why wrong: Incorrect because static routes require Layer 2 connectivity; different bridges are separate Layer 2 domains.
Quick Answer
The answer is to create a new bridge that connects both VNFs or use a virtual switch to route between the bridges. This is necessary because in NFVIS, each bridge network creates an isolated Layer 2 domain, so VNFs attached to different bridges cannot communicate directly, even on the same host. The vASA and vRouter are effectively on separate virtual LANs with no path between them. On the ENCOR 350-401 exam, this tests your understanding of NFVIS bridge connectivity for VNFs and the hypervisor’s role in virtual networking. A common trap is assuming that VNFs on the same host can always talk by default, but NFVIS enforces strict bridge isolation. Remember the memory tip: “Different bridges, different broadcast domains—connect them with a shared bridge or a virtual switch to bridge the gap.”
350-401 Network Function Virtualization Practice Question
This 350-401 practice question tests your understanding of network function virtualization. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company uses Cisco NFVIS to host a virtual ASA (vASA) and a virtual router (vRouter). The engineer notices that the vASA cannot communicate with the vRouter even though both are on the same NFVIS host. The vASA is connected to a bridge network, and the vRouter is connected to a different bridge. What should the engineer do to enable communication between the two VNFs?
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
Create a new bridge that connects both VNFs, or use a virtual switch to route between the bridges.
In NFVIS, VNFs attached to different bridge networks are isolated at Layer 2. To enable communication between them, you must either create a new bridge that connects both VNFs or use a virtual switch (e.g., a Linux bridge with routing enabled) to forward traffic between the two bridges. This allows the VNFs to share a common Layer 2 domain or have a routed path through the hypervisor.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Connect a physical cable between two ports on the NFVIS host.
Why it's wrong here
Incorrect because VNFs are virtual; a physical cable is not used for inter-VNF communication on the same host.
- ✓
Create a new bridge that connects both VNFs, or use a virtual switch to route between the bridges.
Why this is correct
Correct because placing both VNFs on the same bridge allows Layer 2 communication; alternatively, a virtual router can route between bridges.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Configure VLAN tagging on both VNFs with the same VLAN ID.
Why it's wrong here
Incorrect because VLAN tagging alone does not connect different bridges; the bridges must be linked.
- ✗
Add a static route on each VNF pointing to the other VNF's IP address.
Why it's wrong here
Incorrect because static routes require Layer 2 connectivity; different bridges are separate Layer 2 domains.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that VLAN tagging alone can connect VNFs across different bridges, but VLANs only segment traffic within a single bridge and do not create connectivity between separate bridges.
Detailed technical explanation
How to think about this question
NFVIS uses Linux bridges to provide Layer 2 connectivity to VNFs. Each bridge is an isolated broadcast domain. To interconnect VNFs on different bridges, you can create a new bridge and attach both VNFs to it, or use a virtual switch (e.g., Open vSwitch) that can route between bridges. In production, this is often done by deploying a virtual router (like the vRouter itself) to act as a gateway between the bridges, or by using a single bridge for all VNFs that need to communicate.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this 350-401 question test?
Network Function Virtualization — This question tests Network Function Virtualization — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Create a new bridge that connects both VNFs, or use a virtual switch to route between the bridges. — In NFVIS, VNFs attached to different bridge networks are isolated at Layer 2. To enable communication between them, you must either create a new bridge that connects both VNFs or use a virtual switch (e.g., a Linux bridge with routing enabled) to forward traffic between the two bridges. This allows the VNFs to share a common Layer 2 domain or have a routed path through the hypervisor.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 24, 2026
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.
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