The answer is the well-known BGP community NO_EXPORT, which is the correct choice to prevent a specific prefix from being advertised to any external AS. This community, represented as 0xFFFFFF01, instructs the router to withhold the route from all eBGP peers while still allowing it to be shared with iBGP neighbors within the same autonomous system. On the Cisco SPCOR 350-501 exam, this concept tests your understanding of BGP community filtering and route propagation control, often appearing in scenario-based questions where you must distinguish between NO_EXPORT, NO_ADVERTISE, and Local-AS. A common trap is confusing NO_EXPORT with NO_ADVERTISE, which blocks advertisement to all peers including iBGP, making it too restrictive for this requirement. Remember the memory tip: “NO_EXPORT keeps it in the house (your AS), NO_ADVERTISE keeps it a secret from everyone.”
350-501 Architecture Practice Question
This 350-501 practice question tests your understanding of architecture. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 service provider uses BGP communities to influence routing policies. An administrator wants to prevent a specific prefix from being advertised to any external AS. Which BGP community should be applied?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
NO_EXPORT
The well-known community NO_EXPORT (0xFFFFFF01 or 0xFFFFFF01) tells the router not to advertise the prefix to any eBGP peers. The community NO_ADVERTISE prevents advertisement to any peer (including iBGP), which is too restrictive. Local-AS (0xFFFFFF03) prevents advertisement to external AS but allows advertisement to confederation sub-AS. To prevent advertisement to any external AS, NO_EXPORT is correct.
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.
✗
NO_ADVERTISE
Why it's wrong here
NO_ADVERTISE prevents advertisement to any peer, including iBGP, which is too restrictive.
✗
INTERNET
Why it's wrong here
INTERNET community does not affect advertisement.
✗
LOCAL_AS
Why it's wrong here
LOCAL_AS prevents advertisement to external peers but allows within the confederation; it is not the standard community for this purpose.
✗
NONE
Why it's wrong here
NONE is not a valid standard community.
✓
NO_EXPORT
Why this is correct
NO_EXPORT prevents advertisement to any eBGP peer, which is exactly what is needed.
Related concept
Read the scenario before looking for a memorised answer.
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.
Architecture — This question tests Architecture — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: NO_EXPORT — The well-known community NO_EXPORT (0xFFFFFF01 or 0xFFFFFF01) tells the router not to advertise the prefix to any eBGP peers. The community NO_ADVERTISE prevents advertisement to any peer (including iBGP), which is too restrictive. Local-AS (0xFFFFFF03) prevents advertisement to external AS but allows advertisement to confederation sub-AS. To prevent advertisement to any external AS, NO_EXPORT is correct.
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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