CND Network Attacks And Defense Strategies Practice Question
An enterprise network is subjected to a distributed denial-of-service (DDoS) volumetric UDP reflection and amplification attack utilizing Network Time Protocol (NTP) monlist queries. Which configuration change should be applied to enterprise NTP servers to prevent them from participating in amplification attacks?
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
✓
Disable the 'monlist' command and restrict external queries in the ntp.conf configuration file.
The NTP 'monlist' (monitor list) command returns the IP addresses of recent clients interacting with the NTP server, making it a prime vector for UDP amplification attacks. Disabling monlist or upgrading NTP to versions where monlist is disabled by default mitigates this risk.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure NTP authentication using symmetric cryptographic keys for time synchronization.
Why it's wrong here
NTP authentication ensures time synchronization integrity, but does not stop monlist reflection.
- ✗
Enable Unicast Reverse Path Forwarding (uRPF) in strict mode on internal interfaces.
Why it's wrong here
uRPF handles IP routing path verification, not application-level NTP daemon commands.
- ✓
Disable the 'monlist' command and restrict external queries in the ntp.conf configuration file.
Why this is correct
Disabling monlist prevents the NTP server from returning large responses to spoofed small queries.
- ✗
Implement ICMP rate-limiting on the enterprise perimeter routing devices.
Why it's wrong here
ICMP rate-limiting affects ICMP ping traffic, whereas NTP reflection utilizes UDP port 123.
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official EC-Council exam blueprint
This CND practice question is part of Courseiva's free EC-Council 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 CND exam.