How does a client locate a WLAN during passive scanning?

How does a client locate a WLAN during passive scanning?

• A. The client actively searches by sending probe requests on all channels.
• B. The client listens for beacons until it hears a beacon listing the SSID of the network it expects to join.
• C. The client connects to any available network without filtering.
• D. The client relies on DNS to identify the WLAN.

Answer: (B)

Passive scanning works by listening for beacon frames from nearby access points. Beacons are periodic broadcasts that announce the presence of a WLAN and include the network’s SSID along with other details like supported data rates and security capabilities. The client remains quiet, scanning across channels and recording the SSIDs it hears. When a beacon advertises the SSID of the WLAN the client wants to join, the client recognizes that network is in range and can move toward connecting. This contrasts with active scanning, where the client would send probe requests on channels to elicit responses. DNS has no role in locating WLANs. Keep in mind that if a network uses a hidden SSID (not advertised in beacons), passive scanning alone might not reveal the SSID.

Passive scanning works by listening for beacon frames from nearby access points. Beacons are periodic broadcasts that announce the presence of a WLAN and include the network’s SSID along with other details like supported data rates and security capabilities. The client remains quiet, scanning across channels and recording the SSIDs it hears. When a beacon advertises the SSID of the WLAN the client wants to join, the client recognizes that network is in range and can move toward connecting. This contrasts with active scanning, where the client would send probe requests on channels to elicit responses. DNS has no role in locating WLANs. Keep in mind that if a network uses a hidden SSID (not advertised in beacons), passive scanning alone might not reveal the SSID.