CCOA Securing Assets Practice Question
You are configuring a Linux server and want to use 'iptables' to block all incoming traffic from a specific subnet (192.168.10.0/24). Which command is correct?
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 -s 192.168.10.0/24 -j DROP
The 'iptables -A INPUT -s [network] -j DROP' syntax correctly appends a rule to the INPUT chain to drop traffic from the specified source.
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 -I OUTPUT -d 192.168.10.0/24 -j REJECT
Why it's wrong here
This blocks traffic leaving the server to that subnet, not incoming traffic.
- ✗
iptables -A FORWARD -s 192.168.10.0/24 -j DROP
Why it's wrong here
This only blocks traffic being routed through the server, not traffic destined for the server itself.
- ✗
iptables -A INPUT -d 192.168.10.0/24 -j DROP
Why it's wrong here
The '-d' flag refers to the destination of the traffic, not the source subnet.
- ✓
iptables -A INPUT -s 192.168.10.0/24 -j DROP
Why this is correct
This is the correct command structure for blocking a subnet in the INPUT chain.
Visual reference
About these practice questions
This CCOA question is part of Courseiva's 203-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 ISACA exam blueprint
This CCOA practice question is part of Courseiva's free ISACA 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 CCOA exam.