Which of the following ports would have to be allowed through a firewall for POP3 traffic to pass
on its default port?

A.
110

B.
123

C.
143

D.
443

Explanation:
Post Office Protocol (POP) is an application-layer Internet standard protocol used by local e-mail
clients to retrieve e-mail from a remote server over a TCP/IP connection. POP3 server listens
on well-known port 110.