UDP port 69 is used by which protocol?

• A. Hypertext Transfer Protocol (HTTP)
• B. Lightweight Directory Access Protocol (LDAP)
• C. Trivial File Transfer Protocol (TFTP)
• D. Post Office Protocol version 3 (POP3)

Answer: (C)

Port 69 is reserved for Trivial File Transfer Protocol, a simple file transfer service that runs over UDP. TFTP uses this well-known port for the initial read or write request from the client to the server. Because UDP is connectionless, after that first request the actual data transfer occurs on a separate, ephemeral port chosen for the data exchange, with replies coming from the server’s chosen port back to the client. This lightweight design is what makes TFTP specifically associated with UDP port 69.

Other options don’t operate on UDP port 69. HTTP runs over TCP (typically port 80 or 443 for HTTPS), POP3 uses TCP ports like 110 (or 995 for POP3S), and LDAP typically uses port 389 (with LDAPS on 636).