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CISSP Practice Question: Deploying a new web application and needs to…
A company is deploying a new web application and needs to ensure that only HTTPS traffic is allowed. What is the MOST effective way to enforce this at the network perimeter?
⚠ Common exam trap
Candidates often think allowing both ports 80 and 443 is acceptable for flexibility, but the question explicitly requires only HTTPS, so blocking port 80 is essential to enforce encryption at the perimeter.
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
✓
Allow TCP port 443 only and block port 80.
Blocking TCP port 80 and allowing only TCP port 443 at the network perimeter ensures that only HTTPS traffic can enter or leave the network. This is the most effective method because it directly enforces the protocol restriction at the firewall, preventing any HTTP traffic from bypassing encryption. Allowing both ports would permit unencrypted HTTP, while using a proxy or blocking port 443 would either add unnecessary complexity or deny legitimate HTTPS traffic.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Allow TCP port 443 only and block port 80.
Why this is correct
This configuration directly enforces the use of HTTPS by making TCP port 443 (HTTPS) accessible while explicitly denying TCP port 80 (HTTP). It ensures all web traffic to the application is encrypted, meeting security requirements for data confidentiality and integrity. Any attempt to connect via unencrypted HTTP would be blocked at the network perimeter, preventing insecure access and upholding the 'HTTPS-only' mandate.
- ✗
Configure the firewall to allow TCP port 80 and 443.
Why it's wrong here
While allowing both TCP port 80 and 443 permits HTTPS traffic, it simultaneously leaves the unencrypted HTTP channel open. This configuration fails to enforce the 'HTTPS-only' requirement, as clients could still initiate insecure connections on port 80, potentially exposing sensitive data in transit. It provides an option for secure communication but does not mandate it, leaving a critical vulnerability.
- ✗
Use a proxy server to decrypt all traffic.
Why it's wrong here
Using a proxy server to decrypt all traffic is a technique often employed for deep packet inspection or content filtering, but it does not inherently enforce HTTPS-only communication. While the proxy can handle and inspect HTTPS traffic, it doesn't block unencrypted HTTP connections from reaching the application or being processed. Decryption by a proxy is a separate security control from protocol enforcement and does not prevent insecure HTTP access.
- ✗
Block TCP port 443.
Why it's wrong here
Blocking TCP port 443 would completely prevent any HTTPS connections from reaching the web application. Since HTTPS is the secure protocol specifically desired for the application, this action would render the application inaccessible via its intended secure channel. This directly undermines the goal of secure communication and would make the web application unusable for its intended secure purpose.
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Related to this question
Learn chapter
Secure Network Architecture and Components
Key term
Encryption
Encryption is the process of converting readable data into a secret code to prevent unauthorized access.
Key term
Firewall
A firewall is a network security system that monitors and controls incoming and outgoing traffic based on predetermined security rules to protect trusted internal networks from untrusted external networks.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CISSP 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 CISSP exam.