220-1101 Question 71
Single answer3389 – Remote Desktop Protocol (RDP)A technician needs to remotely configure a Windows 10 Pro workstation for a user in another office. The user confirms the PC is powered on and connected to the network. The technician can ping the workstation by IP address, but when trying to open a Remote Desktop session, the connection fails immediately. After reviewing the workstation settings, the technician discovers that Remote Desktop is enabled and the user account has permission to connect. Which port should the technician verify is allowed through the workstation's firewall to restore Remote Desktop access?
- A
TCP 22
- B
TCP 3389
- C
TCP 443
- D
TCP 5900
Show answer and explanation
Correct answer: B
Explanation
This question tests practical troubleshooting of Remote Desktop connectivity. In a real support scenario, if a Windows workstation is reachable on the network, Remote Desktop is enabled, and the account has access, the technician should verify that the firewall permits RDP traffic. Microsoft Remote Desktop Protocol uses TCP 3389 by default, which is a standard A+ Core 1 port number to recognize. Common distractors include SSH on TCP 22, HTTPS on TCP 443, and VNC on TCP 5900. As a best practice, technicians should confirm both Windows Defender Firewall settings and any network firewall rules when troubleshooting blocked RDP access. Microsoft documentation for Remote Desktop identifies TCP 3389 as the default listening port for RDP unless it has been manually changed.
- A. Incorrect.
Incorrect. TCP 22 is used by SSH for secure command-line remote access, primarily on Linux, Unix, and network devices. A technician might choose this because it is a common remote-management port, but it is not the default port for Microsoft Remote Desktop Protocol.
- B. Correct.
Correct. TCP 3389 is the default port used by Microsoft Remote Desktop Protocol (RDP). If Remote Desktop is enabled, the user is authorized, and the system is reachable by ping, the next logical step is to verify that the host-based firewall or any intervening firewall allows RDP traffic on TCP 3389.
- C. Incorrect.
Incorrect. TCP 443 is commonly used for HTTPS web traffic. Someone might select this because many remote-access web portals and secure services use 443, but standard RDP connections use TCP 3389 by default rather than HTTPS.
- D. Incorrect.
Incorrect. TCP 5900 is commonly associated with VNC remote-access software, not Microsoft RDP. This is a plausible distractor because both VNC and RDP are remote desktop technologies, but they use different default ports and protocols.