Which of the following cryptographic algorithms is MOST often used with IPSec?

A.
Blowfish

B.
Twofish

C.
RC4

D.
HMAC

Explanation:
The HMAC-MD5-96 (also known as HMAC-MD5) encryption technique is used by IPSec to make sure that a message has not been altered.
Incorrect Answers:
A: Blowfish can be used with IPSec but not as often as HMAC.
B: Twofish, a variant of Blowfish, can be used with IPSec but not as often as HMAC.
C: RC4 is popular with wireless and WEP/WPA encryption. IPSec can use HMAC-MD5 for data integrity.

Dulaney, Emmett and Chuck Eastton, CompTIA Security+ Study Guide, Sixth Edition, Sybex, Indianapolis, 2014, pp 139, 250, 251, 255-256, 260