Monitor mode is designed for network surveillance; the AP does not serve clients but scans all channels to collect statistics on air quality, detect interference (IDS/IPS), and track the location of RFID tags using RSSI.

Sniffer mode dedicates the AP's radio to a specific frequency (channel) to capture raw 802.11 frames. These captured packets are encapsulated and forwarded to a remote station running analysis software (packet analyzers like Wireshark) for detailed debugging.

Sensor mode (often associated with Cisco Service Assurance or Active Sensors) allows the AP to function as a client device. It runs synthetic tests to generate performance analytics and verify network services (DHCP, DNS, web), enabling engineers to troubleshoot client experiences remotely without being onsite.

Cisco Systems. Cisco Wireless Controller Configuration Guide, Release 8.10, "Chapter: Access Point Modes." Section: Monitor Mode. (Describes scanning all channels, rogue detection, and location tracking).

Cisco Systems. Cisco Wireless Controller Configuration Guide, Release 8.10, "Chapter: Access Point Modes." Section: Sniffer Mode. (Describes capturing packets on a specific channel and forwarding to a remote device).

Cisco Systems. Cisco Aironet Active Sensor Solution Guide, "Overview of Cisco Aironet Active Sensor." (Details the sensor's role in measuring wireless performance, running synthetic tests, and troubleshooting remotely as a client).