CND Network Perimeter Protection Practice Question
A security analyst configuring a Linux-based iptables firewall wants to ensure that any established or related incoming TCP connections are automatically allowed through without hitting subsequent rule checks. Which target and match extension combination should be used?
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
✓
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
Using the connection tracking module (-m conntrack --ctstate ESTABLISHED,RELATED) combined with the -j ACCEPT target allows return traffic for active outbound sessions.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
iptables -A INPUT -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
Why this is correct
This rule correctly matches existing connection states and accepts them.
- ✗
iptables -A INPUT -m limit --limit 5/min -j LOG
Why it's wrong here
This rule logs packet rates rather than managing established states.
- ✗
iptables -A FORWARD -p tcp --dport 80 -j REJECT
Why it's wrong here
This rule rejects HTTP traffic rather than tracking states.
- ✗
iptables -A INPUT -m state --state NEW -j DROP
Why it's wrong here
This rule drops new connections, which would block legitimate incoming traffic.
Visual reference
About these practice questions
This CND question is part of Courseiva's 323-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
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.