- A
MPLS TTL propagation
Why wrong: This affects traceroute visibility, not control plane security.
- B
Unicast Reverse Path Forwarding (uRPF)
uRPF drops packets with spoofed source IPs, reducing attack traffic.
- C
Control Plane Policing (CoPP)
CoPP rate-limits control plane traffic.
- D
BGP prefix filtering
Why wrong: This filters routing updates, not attack traffic.
- E
NTP authentication
Why wrong: NTP authentication secures time synchronization, not control plane attacks.
Question 788 of 1,000
350-501 Security and Services Practice Question
This 350-501 practice question tests your understanding of security and services. 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 wants to protect its core routers from control plane attacks. Which two mechanisms are effective in mitigating such attacks on IOS XR? (Choose two.)
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
✓
Unicast Reverse Path Forwarding (uRPF)
CoPP polices control plane traffic. uRPF prevents spoofed source IPs, which are often used in attacks. BGP prefix filtering is for routing updates, not control plane attacks. MPLS TTL propagation is for traceroute. NTP authentication secures time sync.
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.
- ✗
MPLS TTL propagation
Why it's wrong here
This affects traceroute visibility, not control plane security.
- ✓
Unicast Reverse Path Forwarding (uRPF)
Why this is correct
uRPF drops packets with spoofed source IPs, reducing attack traffic.
Related concept
Read the scenario before looking for a memorised answer.
- ✓
Control Plane Policing (CoPP)
Why this is correct
CoPP rate-limits control plane traffic.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
BGP prefix filtering
Why it's wrong here
This filters routing updates, not attack traffic.
- ✗
NTP authentication
Why it's wrong here
NTP authentication secures time synchronization, not control plane attacks.
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.
Visual reference
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.
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Security and Services — study guide chapter
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Security and Services practice questions
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FAQ
Questions learners often ask
What does this 350-501 question test?
Security and Services — This question tests Security and Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Unicast Reverse Path Forwarding (uRPF) — CoPP polices control plane traffic. uRPF prevents spoofed source IPs, which are often used in attacks. BGP prefix filtering is for routing updates, not control plane attacks. MPLS TTL propagation is for traceroute. NTP authentication secures time sync.
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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Last reviewed: Jul 4, 2026
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.
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