Users report that after downloading several applications, their systems’ performance has noticeably
decreased. Which of the following would be used to validate programs prior to installing them?

A.
Whole disk encryption

B.
SSH

C.
Telnet

D.
MD5

Explanation:
MD5 can be used to locate the data which has changed.
The Message Digest Algorithm (MD) creates a hash value and uses a one-way hash. The hash value is used
to help maintain integrity. There are several versions of MD; the most common are MD5, MD4, and MD2.
Incorrect Answers:
A: Disk encryption would not help in checking integrity of downloaded files.
B: Secure Shell (SSH) is a tunnelling protocol originally used on Unix systems. It is not used to validate the
integrity of files.C: Telnet cannot be used to protect integrity of program files. Telnet is an interactive terminal emulation
protocol. It allows a remote user to conduct an interactive session with a Telnet server. This session can
appear to the client as if it were a local session.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, 6th Edition, Sybex, Indianapolis,
2014, pp. 76, 255, 271, 290