The answer is to use distinct route targets for import and export per VRF. This is correct because route targets (RTs) control which VPN routes are imported into a VRF and which are advertised out; by assigning unique RTs to each overlapping VPN, the provider edge routers will only accept routes tagged with the matching RT, preventing any cross-VPN route leakage even when IP addresses overlap. On the Cisco SPCOR / CCNP Service Provider Core 350-501 exam, this concept tests your understanding of how MPLS L3VPN isolates customer traffic—a common trap is confusing route distinguishers (RDs) with route targets, but remember that RDs only make prefixes unique in the BGP table, while RTs enforce the import/export policies that actually control leaking. A useful memory tip: think of RTs as the “gatekeeper” that decides which VPNs can see each other’s routes, while RDs are just “name tags” to avoid BGP path duplication.
350-501 MPLS and Segment Routing Practice Question
This 350-501 practice question tests your understanding of mpls and segment routing. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
In an MPLS L3VPN network, a customer has overlapping IP addresses between two VPNs. The provider edge routers are configured with VRF instances. Which method ensures that traffic from one VPN does not leak into the other when using MPLS labels?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use distinct route targets for import and export per VRF.
The correct method is to import/export route targets correctly to keep VPN routes separate. Option A is incorrect because route distinguishers only make routes unique, they don't prevent leaking. Option C is incorrect because label allocation is per VRF, but leaking occurs due to route import policies. Option D is incorrect because BGP communities are used for route filtering, but RT is the standard mechanism.
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.
✗
Assign different MPLS label ranges to each VRF.
Why it's wrong here
Label allocation is per VRF, but labels do not prevent route leaking.
✗
Apply BGP community strings to filter routes.
Why it's wrong here
BGP communities can be used, but route targets are the primary mechanism for VPN route distribution.
✓
Use distinct route targets for import and export per VRF.
Why this is correct
RTs control which routes are imported into a VRF, preventing leakage.
Related concept
Read the scenario before looking for a memorised answer.
✗
Configure different route distinguishers for each VPN.
Why it's wrong here
RD makes routes unique but does not control route distribution between VRFs.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
How to think about this question
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
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.
Use explanations to understand the rule behind the answer.
TExam Day Tips
→Underline the problem statement mentally.
→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 350-501 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.
What to study next
Got this wrong? Here's your next step.
Identify which 350-501 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
MPLS and Segment Routing — This question tests MPLS and Segment Routing — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use distinct route targets for import and export per VRF. — The correct method is to import/export route targets correctly to keep VPN routes separate. Option A is incorrect because route distinguishers only make routes unique, they don't prevent leaking. Option C is incorrect because label allocation is per VRF, but leaking occurs due to route import policies. Option D is incorrect because BGP communities are used for route filtering, but RT is the standard mechanism.
What should I do if I get this 350-501 question wrong?
Identify which 350-501 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
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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