Quick Answer
The answer is port 3389, which is the default port used by Remote Desktop Protocol (RDP) for remote graphical connections to Windows servers and workstations. RDP relies on TCP port 3389 to establish a secure session, and if the server’s firewall is not allowing inbound traffic on this specific port, the connection will fail even if outbound traffic is unrestricted. On the CompTIA A+ Core 1 220-1201 exam, this question tests your ability to distinguish common remote-access protocols: port 22 for SSH, port 23 for Telnet, and port 5900 for VNC. A common trap is confusing RDP with SSH, but remember that RDP is for Windows GUI remote control, while SSH is for secure command-line access. To lock in the number, think of the mnemonic “3389: Three Threes, Eight Nine” — or simply recall that RDP and 3389 both start with the letter “R” and “T” (three).
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 user cannot connect to a remote server using RDP. The network team confirms that the firewall allows outbound traffic on all ports. Which port is typically used for RDP and should be verified on the server side?
Port 22
Why wrong: Port 22 is used for SSH, not RDP.
Port 3389
Port 3389 is the default port for Remote Desktop Protocol.
Port 23
Why wrong: Port 23 is used for Telnet, an unencrypted remote access protocol.
Port 5900
Why wrong: Port 5900 is used for VNC, a different remote desktop protocol.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Port 3389
RDP (Remote Desktop Protocol) uses port 3389 by default. Port 22 is for SSH, port 23 for Telnet, and port 5900 for VNC. If the server's firewall is not allowing inbound traffic on port 3389, the RDP connection will fail.
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.
Port 22
Why it's wrong here
Port 22 is used for SSH, not RDP.
Port 3389
Why this is correct
Port 3389 is the default port for Remote Desktop Protocol.
Related concept
Read the scenario before looking for a memorised answer.
Port 23
Why it's wrong here
Port 23 is used for Telnet, an unencrypted remote access protocol.
Port 5900
Why it's wrong here
Port 5900 is used for VNC, a different remote desktop protocol.
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.
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FAQ
TCP & UDP Ports — This question tests TCP & UDP Ports — Read the scenario before looking for a memorised answer..
The correct answer is: Port 3389 — RDP (Remote Desktop Protocol) uses port 3389 by default. Port 22 is for SSH, port 23 for Telnet, and port 5900 for VNC. If the server's firewall is not allowing inbound traffic on port 3389, the RDP connection will fail.
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.
Read the scenario before looking for a memorised answer.
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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.
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