Which of the following is not an effective countermeasure against replay attacks?

A.
Digital signatures

B.
Time Stamps

C.
System identification

D.
Sequence numbers

Explanation:
A replay attack is a form of network attack in which a valid data transmission is
maliciously or fraudulently repeated or delayed. Effective countermeasures should be anything
that makes it hard to delay or replay the packet (time stamps and sequence numbers) or anything
that prove the package is received as it was sent from the original sender (digital signature)