Blake is an IT security consultant, specializing in PBX and VoIP implementation testing. Blake has been recently hired on my Thwarting Enterprises, a brokerage firm in New York City. The company heard through contacts that Blake was t he best in the business as far as examining and securing VoIP network implementations. About a year ago, Thwarting Enterprises installed a Cisco VoIP system throughout their office to replace the older PBX system. They have now brought Blake in to test its security, or lack thereof. Blake first begins his testing byfinding network devices on the network that might be used for VoIP. Blake pref ers to use UDP scanning because of its quickness. Blake finds a target on the network that looks promising and begins to perform a scan against it by sending p ackets with empty UDP headers to each port. Almost all of the ports respond with the error of “ICMP port unreachable”. From these errors, what can Blake deduce about these ports?
A.
From this error, Blake can tell that these ports are not being used.
B.
This specific error means that the ports are currently in stealth mode.
C.
Blake can deduce that the ports that respond with this error are open and listening.
D.
He can tell that these specific ports are in hybrid mode.
Correct answer is A