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.
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.
80
Why wrong: Port 80 is HTTP, which is working since HTTP sites load.
443
Port 443 is HTTPS. Blocking it prevents secure web traffic while allowing unencrypted HTTP.
22
Why wrong: Port 22 is SSH, used for secure remote administration, not web browsing.
53
Why wrong: Port 53 is DNS, used for name resolution, not web traffic.
Answer choices
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 port 443 for secure web traffic. If port 443 is blocked, HTTPS sites won't load, but HTTP (port 80) will still work.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
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
Many certification questions include familiar terms but test a specific constraint. Read the exact wording before choosing an answer that is generally true but wrong for this case.
Detailed technical explanation
This question should be treated as a scenario, not a definition check. Identify the problem, the constraint and the best action. Then compare each option against those facts.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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.
What to study next
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
TCP & UDP Ports — study guide chapter
Learn the concepts, then practise the questions
TCP & UDP Ports practice questions
Targeted practice on this topic area only
All 220-1201 questions
1,020 questions across all exam domains
CompTIA A+ Core 1 220-1201 study guide
Full concept coverage aligned to exam objectives
220-1201 practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise 220-1201 questions linked to Mobile Device Hardware Servicing.
Practise 220-1201 questions linked to Mobile Device Connection Methods.
Practise 220-1201 questions linked to Mobile Device Accessories.
Practise 220-1201 questions linked to Mobile Device Network Connectivity.
Practise 220-1201 questions linked to Mobile Device Application Support.
Practise 220-1201 questions linked to Network Protocols.
Practise 220-1201 questions linked to TCP & UDP Ports.
Practise 220-1201 questions linked to Wireless Networking Technologies.
Practise 220-1201 questions linked to Network Services.
Practise 220-1201 questions linked to Network Configuration Concepts.
Practise 220-1201 questions linked to Common Networking Hardware.
Practise 220-1201 questions linked to IP Addressing.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
TCP & UDP Ports — This question tests TCP & UDP Ports — Read the scenario before looking for a memorised answer..
The correct answer is: 443 — HTTPS uses port 443 for secure web traffic. If port 443 is blocked, HTTPS sites won't load, but HTTP (port 80) will still work.
Identify which 220-1201 exam domain this question belongs to, then review the specific concept being tested. Practise related questions in that domain and focus on understanding why each wrong answer is tempting — not just why the correct answer is right.
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Keep practising
Last reviewed: Jun 18, 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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.