Product and Software: This article applies to all Aruba controllers and ArubaOS versions.
When the hide SSID feature is enabled, the AP is forced to use 'NULL' SSID instead of actual SSID in 802.11 beacons.
If the deny broadcast feature is enabled, the AP is prevented from responding to broadcast probe requests.
Except for probe responses, SSID is included in association and re-association frames, which are always sent in clear and can be easily parsed by any listening device. This is the reason why many tools like NetStumbler can still see a hidden SSID.