rexec uses which port number?

rexec uses which port number?

• A. 2049
• B. 512
• C. 3389
• D. 161

Answer: (B)

Rexec is one of the older BSD remote command tools that uses a fixed well-known port for its service. The server runs a daemon that listens specifically on port 512, and clients connect to that port to request execution of a command on the remote host and receive the output. This fixed-port convention is why port 512 is the correct choice for rexec. To place it in context, other common administrative services use different ports: for example, NFS uses 2049, Remote Desktop uses 3389, and SNMP uses 161. The key idea is that rexec’s role is remote command execution, and its designated port is 512, whereas the others are tied to their own distinct services. Remember, these old services can be insecure because they transmit credentials in plaintext, so SSH is preferred today for secure remote command execution.

Rexec is one of the older BSD remote command tools that uses a fixed well-known port for its service. The server runs a daemon that listens specifically on port 512, and clients connect to that port to request execution of a command on the remote host and receive the output. This fixed-port convention is why port 512 is the correct choice for rexec.

To place it in context, other common administrative services use different ports: for example, NFS uses 2049, Remote Desktop uses 3389, and SNMP uses 161. The key idea is that rexec’s role is remote command execution, and its designated port is 512, whereas the others are tied to their own distinct services. Remember, these old services can be insecure because they transmit credentials in plaintext, so SSH is preferred today for secure remote command execution.