If ip helper address is used on the gateway interface for the AP management network, and points to the WLC that is serving the IP's, does the WLC send Option 43 to the AP's? I have been setting up local DHCP pools on the routers for each location, but haven't tried to forward the DHCP requests to the WLC in this type of setup where the WLC is colocated centrally from all the sites.
The WLC when used as a dhcp server doesn't send Option 43. If you are trying to use ip helper then you need to also use ip forward protocol udp 12222 and ip forward protocol udp 12223. This is the way you can forward the join broadcast to the WLC without the need of option 43 or DNS.
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Transferring Crash file from standby: Login to the Active WLC in HA.
From CLI: (Cisco Controller) >transfer upload datatype crash (Cisco
Controller) >transfer upload filename (Cisco
Controller) >transfer upload mode tftp (Cisco Controller) >transfer
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