Which statement is TRUE about the operation of a packet sniffer?

A.
It can only have one interface on a management network.

B.
They are required for firewall operation and stateful inspection.

C.
The Ethernet card must be placed in promiscuous mode.

D.
It must be placed on a single virtual LAN interface.

Explanation:
A sniffer (packet sniffer) is a tool that intercepts data flowing in a network. If computers are
connected to a local area network that is not filtered or switched, the traffic can be broadcast to all
computers contained in the same segment. This doesn’t generally occur, since computers are
generally told to ignore all the comings and goings of traffic from other computers. However, in the

case of a sniffer, all traffic is shared when the sniffer software commands the Network Interface
Card (NIC) to stop ignoring the traffic. The NIC is put into promiscuous mode, and it reads
communications between computers within a particular segment. This allows the sniffer to seize
everything that is flowing in the network, which can lead to the unauthorized access of sensitive
data. A packet sniffer can take the form of either a hardware or software solution. A sniffer is also
known as a packet analyzer.