Which two statements about beacon frames used by access points are true? (Choose two.)
A . They contain SSIDs if this feature is enabled.
B . They provide vendor proprietary information.
C . They are another name for an associated request.
D . They are sent in response to a probe frame.
E . They include ATIM window information for power save operations.
Answer: AB
Explanation:
Probably the most common 802.11 management frame is the beacon frame.
Beacon frame from a Cisco WLAN
Here we can easily make out some of the capabilities of the WLAN, for example the SSID is probably going to be the first thing you notice TestSSID in this case, this is what provides the name of the WLAN. As you know SSID broadcasting can be disabled (Also called Closed System) at which point the SSID field will be blank.
Now, at the end of the beacon frame you will notice all this Unknown information, as you have probably guessed (or read) this information is vendor specific, which is common for every vendor to have put their own proprietary information within the Beacon frames.
http://ccie-or-null.net/2011/06/22/802-11-beacon-frames/