It’s not really counted that way



What commonly uses port tcp/25?

A) SMTP

B) DNS

C) POP3

D) RDP

E) The server after port 24, but before port 26


The answer: A) SMTP

Simple Mail Transfer Protocol uses TCP port 25 as its well-known server port

Want to know more? Watch “Common TCP and UDP Ports.”

TCP and UDP are the primary transport protocols used in today’s modern networks. In this videos, you’ll get an operational overview of the TCP and UDP protocols, and you’ll learn the TCP and UDP ports that will be important to know for your CompTIA A+ exam.