CompTIA Security+ Question H-80

Which device monitors network traffic in a passive manner?

A. Sniffer
C. Firewall
D. Web browser

Answer: A

A sniffer is another name for a protocol analyzer. A protocol analyzer performs its function in a passive manner. In other words, computers on the network do not know that their data packets have been captured. A Protocol Analyzer is a hardware device or more commonly a software program used to capture network data communications sent between devices on a network. Capturing packets sent from a computer system is known as packet sniffing. Well known software protocol analyzers include Message Analyzer (formerly Network Monitor) from Microsoft and Wireshark (formerly Ethereal).
