John is using Firewalk to test the security of his Cisco PIX firewall. He is also utilizing a sniffer located on a subnet that resides deep inside his network. After analyzing the sniffer log files, he does not see any of the traffic produced by Firewalk. Why is that?
A.
Firewalk sets all packets with a TTL of zero
B.
Firewalk cannot pass through Cisco firewalls
C.
Firewalk sets all packets with a TTL of one
D.
Firewalk cannot be detected by network sniffers
