What Does Protocol Normalization Do

What does protocol normalization do?

A) compares evaluated packets to normal, daily network-traffic patterns
B) removes any protocol-induced or protocol-allowable ambiguities
C) compares a packet to related traffic from the same session, to determine whether the packet is out of sequence
D) removes application layer data, whether or not it carries protocol-induced anomalies, so that packet headers can be inspected more accurately for signs of abuse