Signed digital certificates used to secure communication with a web server are MOST commonly
associated with which of the following ports?

A.
25

B.
53

C.
143

D.
443

Explanation:
HTTPS authenticates the website and corresponding web server with which one is
communicating. HTTPS makes use of port 443.
Incorrect Options:
A: Port 25 is used by Simple Mail Transfer Protocol (SMTP) for routing e-mail between mail
servers.
B: Port 53 is used by Domain Name System (DNS).
C: Port 143 is used by Internet Message Access Protocol (IMAP) for the management of email
messages.

https://en.wikipedia.org/wiki/HTTPS
https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers