You can see this by looking at the regulatory domain profile in use on the controller for that region ad checking the allowed channels. The Aruba controller will not select the DFS channels as 'allowed' for ARM to assign to the APs due to the concerns of interference from satellite and radar transmissions, if you select 5 GHz, the DFS channels will not be used until you enable them.

In a default configuration, 13 of the available 22 (20 MHz) 5 GHz channels in the US are subject to Dynamic Frequency Selection (DFS) rules. The concept of DFS is to have the unlicensed device detect the presence of a radar system on the channel they are using and, if the level of the radar is above a certain threshold, vacate that channel and select an alternate channel. This article applies to Aruba Mobility Controllers running ArubaOS version 6.2.0.0 and aboveĭFS is a mechanism to allow unlicensed devices to use the 5 GHz frequency bands already allocated to radar systems without causing interference to those radars.

What is Dynamic Frequency Selection (DFS) ? How to Enable it ? What are the Aruba AP's that supports DFS ?