Which of the following ports would be blocked if Pete, a security administrator, wants to deny access to
websites?

A.
21

B.
25

C.
80

D.
3389

Explanation:
Port 80 is used by HTTP, which is the foundation of data communication for the World Wide Web.
Incorrect Answers:
A: FTP uses TCP port 21.B: SMTP uses TCP port 25.
D: Remote Desktop Protocol (RDP) uses TCP port 3389.

Stewart, James Michael, CompTIA Security+ Review Guide, Sybex, Indianapolis, 2014, pp. 51, 52