Which of the following software allows a network administrator to inspect the protocol header in
order to troubleshoot network issues?

A.
URL filter

B.
Spam filter

C.
Packet sniffer

D.
Switch

Explanation:
Every data packet transmitted across a network has a protocol header. To view a protocol header,
you need to capture and view the contents of the packet with a packet sniffer.
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.