Question 475 of 500
NetworkingmediumMultiple ChoiceObjective-mapped

Quick Answer

The answer is the NO_EXPORT BGP community. This community, defined in RFC 1997, instructs a router to advertise the route to all iBGP peers within the same autonomous system but never to any eBGP peers. In the given scenario, the ISP wants to prevent a customer’s routes from being advertised to a specific transit provider, which is an external eBGP neighbor; applying NO_EXPORT ensures those routes remain confined within the ISP’s AS and are not leaked to any external transit provider. On the Cisco SPCOR 350-501 exam, this concept tests your understanding of BGP path manipulation and community-based filtering, often appearing in scenario-based questions where you must choose the correct community to control route propagation to specific neighbors. A common trap is confusing NO_EXPORT with NO_ADVERTISE, which blocks all advertisements (including to iBGP), or with LOCAL_AS, which only prevents advertisement to confederation peers. For a quick memory tip, think of NO_EXPORT as “keep it in the house”—the route stays within your own AS and never crosses the border to an external neighbor.

350-501 Networking Practice Question

This 350-501 practice question tests your understanding of networking. 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.

An ISP is implementing BGP communities to influence routing behavior for their customers. They want to ensure that a customer's routes are not advertised to a specific transit provider. Which BGP community should be used?

Question 1mediummultiple choice
Open the full BGP breakdown →

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

NO_EXPORT

The NO_EXPORT community (RFC 1997) tells a router to advertise the route to iBGP peers within the same AS but not to any eBGP peers. In this scenario, the ISP wants to prevent a customer's routes from being advertised to a specific transit provider, which is an eBGP neighbor. Applying the NO_EXPORT community to those routes ensures they stay within the ISP's AS and are not sent to any external transit provider.

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.

  • LOCAL_AS

    Why it's wrong here

    LOCAL_AS is not a BGP community; it is a feature for AS-path prepending.

  • NO_EXPORT

    Why this is correct

    This community ensures the route stays within the local AS and is not sent to any external AS.

    Related concept

    Read the scenario before looking for a memorised answer.

  • NO_PEER

    Why it's wrong here

    There is no standard BGP community named NO_PEER.

  • NO_ADVERTISE

    Why it's wrong here

    This community prevents advertisement to any BGP peer, including internal peers.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Cisco often tests the distinction between NO_EXPORT and NO_ADVERTISE, where candidates mistakenly choose NO_ADVERTISE because they think it only blocks eBGP advertisements, but in reality NO_ADVERTISE blocks all advertisements (including iBGP), making NO_EXPORT the correct choice when the goal is to block only external (eBGP) propagation.

Detailed technical explanation

How to think about this question

Under the hood, the NO_EXPORT community is a well-known transitive community that is checked during the BGP best-path selection and update process; when a route carries this community, the router will not send it to any eBGP neighbor, but it will still propagate it to iBGP peers within the same AS. In real-world ISP deployments, NO_EXPORT is commonly used to keep customer routes within a provider's network when the customer does not want their prefixes announced to upstream transit providers, often combined with route maps to match and set the community on specific prefixes.

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 network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.

What to study next

Got this wrong? Here's your next step.

Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.

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FAQ

Questions learners often ask

What does this 350-501 question test?

Networking — This question tests Networking — Read the scenario before looking for a memorised answer..

What is the correct answer to this question?

The correct answer is: NO_EXPORT — The NO_EXPORT community (RFC 1997) tells a router to advertise the route to iBGP peers within the same AS but not to any eBGP peers. In this scenario, the ISP wants to prevent a customer's routes from being advertised to a specific transit provider, which is an eBGP neighbor. Applying the NO_EXPORT community to those routes ensures they stay within the ISP's AS and are not sent to any external transit provider.

What should I do if I get this 350-501 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 25, 2026

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