The correct conclusion is that the VRF supports both IPv4 and IPv6 VPNs with matching route-targets, as the output explicitly lists separate address family sections for IPV4 unicast and IPV6 unicast, each configured with the same export and import route-target community RT:65000:100. This dual-stack configuration allows a single VRF to carry both IPv4 and IPv6 traffic over MPLS L3VPN services, which is a key requirement for modern networks transitioning to IPv6 while maintaining legacy IPv4 support. On the ENCOR 350-401 exam, this scenario tests your ability to interpret the show vrf detail command and recognize that a VRF can be address-family aware—a common trap is assuming a VRF only supports one protocol unless both address families are explicitly shown. Remember the memory tip: “Two stacks, one RT—IPv4 and IPv6 share the same community key.”
350-401 VRF and Path Isolation Practice Question
This 350-401 practice question tests your understanding of vrf and path isolation. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 network engineer runs the following command on Router R2:
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The VRF supports both IPv4 and IPv6 VPNs with matching route-targets
The output shows both 'Address family IPV4 unicast' and 'Address family IPV6 unicast' sections, each with the same export and import route-target communities (RT:65000:100). This confirms the VRF CUSTOMER-B supports both IPv4 and IPv6 VPN address families with matching route-targets, enabling MPLS L3VPN services for both address families over the same VRF.
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.
✗
The VRF is configured for IPv4 only
Why it's wrong here
Both IPv4 and IPv6 address families are listed.
✗
The VRF uses different route-targets for import and export
Why it's wrong here
Both import and export use the same RT:65000:100.
✓
The VRF supports both IPv4 and IPv6 VPNs with matching route-targets
Why this is correct
Both address families are present and use the same route-target for import and export.
Related concept
Read the scenario before looking for a memorised answer.
✗
The VRF has no interfaces assigned
Why it's wrong here
Two interfaces are listed under Interfaces.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that a VRF supports only one address family (IPv4) by default, but the 'show vrf detail' output clearly shows separate address family sections, and candidates may overlook the IPv6 unicast section if they focus only on the route-target values.
Detailed technical explanation
How to think about this question
In MPLS L3VPN, a VRF can be configured with multiple address families (IPv4 and IPv6) under the same VRF instance, each with its own route-target import/export policies. The 'show vrf detail' command reveals these per-address-family configurations, which are critical for dual-stack VPN deployments where both IPv4 and IPv6 routes must be exchanged with the same set of PE routers. The matching route-targets ensure that routes from both address families are imported and exported consistently across the MPLS network.
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 practitioner preparing for the 350-401 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
VRF and Path Isolation — This question tests VRF and Path Isolation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The VRF supports both IPv4 and IPv6 VPNs with matching route-targets — The output shows both 'Address family IPV4 unicast' and 'Address family IPV6 unicast' sections, each with the same export and import route-target communities (RT:65000:100). This confirms the VRF CUSTOMER-B supports both IPv4 and IPv6 VPN address families with matching route-targets, enabling MPLS L3VPN services for both address families over the same VRF.
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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Question Discussion
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