What port must be open for Windows instances to enable remote control via Remote Desktop Protocol (RDP)?

To enable Remote Desktop Protocol (RDP) access for Windows instances, the specific port that must be open is port 3389. RDP uses this port by default for establishing a remote desktop session. When a user attempts to connect to a Windows instance using RDP, the connection request is sent to port 3389 on the target machine.

If this port is not open in the instance's security group or network ACL (Access Control List), the connection attempts will be unsuccessful, preventing remote access. It is essential for administrators to ensure that this port is properly configured to allow inbound traffic from relevant IP addresses to facilitate remote management of the Windows instances.

The other ports mentioned in the choices serve different purposes; for example, port 22 is typically used for SSH connections to Linux servers, and port 8080 is often used for web traffic or proxy servers. Port 3306 is the default port for MySQL database connections. Therefore, these ports do not relate to RDP access for Windows instances.