POP3 over SSL uses which port number?

POP3 over SSL uses which port number?

• A. 110
• B. 995
• C. 563
• D. 17

Answer: (B)

POP3 over SSL is the secure version of the POP3 email retrieval protocol that encrypts the session from the start. The standard POP3 uses port 110 in its unencrypted form, while the secure variant—often called POP3S—operates on port 995 so TLS/SSL starts immediately as the connection is made. The other ports listed correspond to different services (for example, 563 is NNTP over TLS, and 17 is the QOTD service), not POP3. So the correct port for POP3 over SSL is 995.

POP3 over SSL is the secure version of the POP3 email retrieval protocol that encrypts the session from the start. The standard POP3 uses port 110 in its unencrypted form, while the secure variant—often called POP3S—operates on port 995 so TLS/SSL starts immediately as the connection is made. The other ports listed correspond to different services (for example, 563 is NNTP over TLS, and 17 is the QOTD service), not POP3. So the correct port for POP3 over SSL is 995.