CompTIA: Advanced Security Practitioner (CASP) Exam Prep

Answer: D - Sniffers monitor network traffic, captures it, logs it and makes it available for display and analysis. They were originally designed for network maintenance and troubleshooting, but they are increasingly being used by hackers.

Key Takeaway: Sniffing is the electronic form of eavesdropping on communications that computers transmit across networks. A sniffer asks the NIC to stop ignoring all the traffic headed to other computers and pay attention to them. It places the NIC in a state known as promiscuous mode to perform this action. Passive sniffing is mostly performed by putting the sniffer on the same collision domain as the network segment being analyzed. This is usually accomplished by putting the sniffer on a hub, tap, or other pass-through device on the segment. All the person using the sniffer must do is start the sniffer and wait for a device on the same collision domain to start sending or receiving data.