easyMultiple ChoiceObjective-mapped
XK0-006 Practice Question: Refer to the exhibit
Network Topology
Refer to the exhibit. After adding a firewall rule, the web server becomes unreachable from the internal network 192.168.1.0/24. Which line is the cause?
⚠ Common exam trap
The trap here is that candidates may focus on the source IP restriction in option D and assume it is the cause, overlooking the fact that iptables processes rules in order and a preceding DROP rule for the same port will block all traffic, including from the allowed subnet.
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
✓
Line: -A INPUT -p tcp --dport 80 -j DROP
The firewall rule `-A INPUT -p tcp --dport 80 -j DROP` explicitly drops all incoming TCP traffic destined for port 80, regardless of source. Since the web server listens on port 80, this rule blocks all HTTP requests, including those from the internal network 192.168.1.0/24. The rule is placed before any ACCEPT rule for the same port, so the DROP action takes precedence, making the server unreachable.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Default policy (INPUT ACCEPT)
Why it's wrong here
Default policy is ACCEPT; the DROP rule overrides.
- ✗
Missing rule for RELATED traffic
Why it's wrong here
Not relevant; the issue is rule order.
- ✓
Line: -A INPUT -p tcp --dport 80 -j DROP
Why this is correct
This rule drops all HTTP traffic, including from 192.168.1.0/24, before an ACCEPT rule.
- ✗
Line: -A INPUT -p tcp --dport 80 -s 192.168.1.0/24 -j ACCEPT
Why it's wrong here
This rule is not reached because the DROP rule comes first.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This XK0-006 practice question is part of Courseiva's free CompTIA 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 XK0-006 exam.