- A
80
Why wrong: Port 80 is HTTP, which is working since HTTP sites load.
- B
443
Port 443 is HTTPS. Blocking it prevents secure web traffic while allowing unencrypted HTTP.
- C
22
Why wrong: Port 22 is SSH, used for secure remote administration, not web browsing.
- D
53
Why wrong: Port 53 is DNS, used for name resolution, not web traffic.
Question 709 of 1,020
HTTPS Port: 443
This 220-1201 practice question tests your understanding of tcp & udp ports. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A customer complains that their web browser cannot load any HTTPS websites, but HTTP sites work fine. The firewall is configured to allow common ports. Which port is most likely being blocked?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Quick Answer
The answer is port 443, as this is the default port used by the HTTPS protocol to establish encrypted, secure web traffic. When a firewall blocks port 443, the browser cannot complete the TLS handshake required for secure connections, which is why HTTPS sites fail to load while HTTP sites—which rely on port 80—continue to function normally. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of common TCP and UDP port assignments, a frequent objective in the networking domain. A common trap is confusing port 443 with port 80 or port 3389 (RDP), so remember that any time a user can browse HTTP but not HTTPS, the firewall is likely blocking port 443. A simple memory tip: think of “443” as “4-4-3” for “Secure Web,” since the number 4 resembles the letter “S” in a mirror, reinforcing that HTTPS is the secure version of HTTP.
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 uses TCP port 443 for encrypted communication via TLS/SSL. If HTTP (port 80) works but HTTPS fails, the firewall is likely blocking outbound or inbound traffic on port 443, even though it allows common ports. This prevents the browser from establishing the secure connection required for HTTPS websites.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
80
Why it's wrong here
Port 80 is HTTP, which is working since HTTP sites load.
- ✓
443
Why this is correct
Port 443 is HTTPS. Blocking it prevents secure web traffic while allowing unencrypted HTTP.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
22
Why it's wrong here
Port 22 is SSH, used for secure remote administration, not web browsing.
- ✗
53
Why it's wrong here
Port 53 is DNS, used for name resolution, not web traffic.
Common exam traps
Common exam trap: answer the scenario, not the keyword
In CompTIA A+ 220-1101, a common trap is that many candidates assume 'common ports' includes HTTPS (port 443) by default, but the CompTIA objectives note that port 443 must be explicitly allowed for HTTPS. The symptom of HTTP working but HTTPS failing is a classic indicator of a blocked port 443.
Detailed technical explanation
How to think about this question
HTTPS relies on a TCP handshake followed by a TLS handshake on port 443; if the firewall blocks that port, the SYN packet never reaches the server, causing a timeout or connection reset. In real-world scenarios, administrators may inadvertently block port 443 while allowing port 80 in a 'common ports' rule, especially if they forget to include HTTPS in the policy. Tools like `telnet` or `Test-NetConnection` can verify port 443 accessibility from the client.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Visual reference
What to study next
Got this wrong? Here's your next step.
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TCP & UDP Ports — study guide chapter
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FAQ
Questions learners often ask
What does this 220-1201 question test?
TCP & UDP Ports — This question tests TCP & UDP Ports — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: 443 — HTTPS uses TCP port 443 for encrypted communication via TLS/SSL. If HTTP (port 80) works but HTTPS fails, the firewall is likely blocking outbound or inbound traffic on port 443, even though it allows common ports. This prevents the browser from establishing the secure connection required for HTTPS websites.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Last reviewed: Jul 4, 2026
This 220-1201 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 220-1201 exam.
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