easyMultiple Choice
ISC2 CC Practice Question: Is configuring a firewall rule to allow inbound…
A network engineer is configuring a firewall rule to allow inbound HTTPS traffic to a web server. Which port must be opened?
⚠ Common exam trap
ISC2 often tests the distinction between HTTP (port 80) and HTTPS (port 443), and the trap here is that candidates confuse the two or assume HTTPS uses port 80 because both are web protocols.
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
✓
443
HTTPS (HTTP Secure) uses TLS/SSL encryption over TCP port 443 by default. To allow inbound HTTPS traffic to a web server, the firewall rule must permit TCP destination port 443. Port 80 is used for unencrypted HTTP, not HTTPS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
3389
Why it's wrong here
Port 3389 carries RDP for Windows remote desktop, not HTTPS, so inbound web traffic would be blocked. It is tempting because it is a well-known inbound management port, and would be correct when allowing remote desktop access to a Windows host.
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22
Why it's wrong here
Port 22 carries SSH for remote shell access, not HTTPS. It tempts engineers managing Linux web servers, where SSH is the standard administrative channel, but opening it satisfies no browser TLS requirement; HTTPS terminates on 443.
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80
Why it's wrong here
Port 80 serves unencrypted HTTP, so browsers reaching it get plaintext, not TLS-protected sessions. It is tempting because port 80 is the traditional web default and often redirects to 443, but the rule must permit 443 itself.
- ✓
443
Why this is correct
Port 443 carries HTTPS over TLS, satisfying the stem's requirement for inbound secure web traffic. The firewall must permit TCP 443 so clients can establish encrypted sessions with the web server; port 80 would only serve unencrypted HTTP. This directly matches the HTTPS constraint rather than any alternative service.
Go deeper
Related to this question
Learn chapter
Network Security Components and Controls
Key term
TCP
TCP is a connection-oriented transport layer protocol that ensures reliable, ordered, and error-checked delivery of data between applications over IP networks.
Key term
Hypertext Transfer Protocol Secure
Hypertext Transfer Protocol Secure, or HTTPS, is the secure version of HTTP that encrypts data between a web browser and a website using SSL/TLS to protect sensitive information like passwords and credit card numbers.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CC practice question is part of Courseiva's free ISC2 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 CC exam.