The answer is to apply inbound route filtering using prefix lists. This is the correct first action because high CPU usage on a BGP-speaking router is typically driven by the overhead of processing and storing a large number of incoming BGP updates; inbound prefix lists allow the router to discard unwanted routes before they enter the routing table and the BGP process, directly reducing the CPU cycles spent on route computation and memory allocation without impacting existing traffic flows. On the Cisco SPCOR 350-501 exam, this question tests your understanding of BGP scalability and the principle of filtering at the earliest point in the path—a common trap is to immediately adjust timers or reconfigure neighbors, which can disrupt peering or cause route flapping. Remember the memory tip: “Filter first, fix the load—inbound stops the flood.”
350-501 Networking Practice Question
This 350-501 practice question tests your understanding of networking. 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 service provider is experiencing high CPU usage on a router running BGP. Which action should be taken first to mitigate the issue without disrupting traffic?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Apply inbound route filtering using prefix lists.
High CPU usage on a BGP-speaking router is often caused by processing a large number of BGP updates. Applying inbound route filtering using prefix lists (option C) reduces the number of routes the router must process and store, directly lowering CPU load without disrupting existing traffic flows. This is a non-disruptive, targeted mitigation that addresses the root cause of excessive route processing.
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.
✗
Disable BGP on the router.
Why it's wrong here
Disabling BGP would disrupt all BGP traffic, causing an outage.
✗
Increase the BGP keepalive timer.
Why it's wrong here
Keepalive timer affects session keepalives, not the processing load of route updates.
✓
Apply inbound route filtering using prefix lists.
Why this is correct
Filtering unnecessary inbound routes reduces the number of prefixes the router must process, lowering CPU utilization.
Clue confirmation
The clue word "first" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Implement BGP route dampening.
Why it's wrong here
Route dampening addresses flapping routes, not high CPU usage from many BGP prefixes.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that route dampening is a first-line CPU mitigation tool, when in fact it is a stability mechanism for flapping routes and can itself be CPU-intensive; the correct first step is to filter unwanted routes at the point of entry.
Detailed technical explanation
How to think about this question
BGP route filtering with prefix lists works by comparing incoming BGP updates against a configured sequence of permit/deny statements, using longest-prefix-match logic. This filtering occurs before the routes are installed in the BGP table or the RIB, thus preventing unnecessary CPU cycles for route selection and adjacency building. In a real-world scenario, a service provider peering with multiple transit providers might receive full Internet routing tables (~1M routes); applying a prefix list to accept only customer prefixes can reduce CPU usage by orders of magnitude.
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 350-501 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 exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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: Apply inbound route filtering using prefix lists. — High CPU usage on a BGP-speaking router is often caused by processing a large number of BGP updates. Applying inbound route filtering using prefix lists (option C) reduces the number of routes the router must process and store, directly lowering CPU load without disrupting existing traffic flows. This is a non-disruptive, targeted mitigation that addresses the root cause of excessive route processing.
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.
Are there clue words in this question I should notice?
Yes — watch for: "first". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 350-501 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 350-501 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.