Which of the following cannot be detected by intrusion detection systems?

A.
Brute force attack from thin clients and dumb terminals

B.
An internal attack

C.
A DoS attack

D.
An attack coming in through an SSL connection

Explanation:
An intrusion detection system will not be able to detect an attack
that is encrypted. SSL is a protocol that encrypts a full communication channel,
thus if an attack was coming through this channel the IDS could not identify it. IDS
should be able to detect the other mentioned attacks.