XK0-006 Security Practice Question
A technician needs to ensure a service can listen on TCP port 8443 using firewalld. Which command permanently adds the port to the default zone?
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
✓
firewall-cmd --add-port=8443/tcp --permanent
The correct syntax is firewall-cmd --add-port=8443/tcp --permanent. The other options either omit the protocol, use incorrect syntax, or forget --permanent.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
firewall-cmd --add-port=8443/tcp --permanent
Why this is correct
The `--permanent` flag writes the rule to firewalld's persistent configuration rather than only the runtime set, satisfying the requirement to add the port permanently. Without it, the change would vanish on reload or reboot. The command targets the default zone automatically, so no `--zone` argument is needed.
- ✗
firewall-cmd --add-port=8443 --permanent
Why it's wrong here
Omitting /tcp leaves the protocol unspecified, and firewalld requires port entries in port/protocol form, so the command errors rather than adding the rule. It is tempting because --permanent is correctly present; the syntax is right for a port that already carries an explicit protocol suffix.
- ✗
firewall-cmd --add-port=8443/tcp
Why it's wrong here
Missing --permanent; the rule will not persist after reload.
- ✗
firewall-cmd --add-service=8443/tcp --permanent
Why it's wrong here
--add-service expects a named service definition from /usr/lib/firewalld/services, not a port/protocol pair, so 8443/tcp is rejected as an unknown service. It is tempting because --add-service is the right approach when a predefined service such as https already maps the required ports.
Go deeper
Related to this question
Learn chapter
Firewall and Security Basics
Key term
firewalld
firewalld is a dynamic firewall management tool for Linux systems that controls incoming and outgoing network traffic using zones and rules.
Key term
Service
A service is a software component or system that performs a specific function and is available to be used by other programs or users over a network.
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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.