An engineer is troubleshooting the AP join process using DNS. Which FQDN must be resolvable on the network for the access points to successfully register to the WLC?

`wlchostname.domain.com` is a generic hostname and not the specific FQDN used by Cisco APs for WLC discovery via DNS.

Cisco APs use the `cisco-capwap-controller` DNS entry as a primary mechanism to discover a WLC, allowing them to establish a CAPWAP tunnel for registration. The WLC's IP address must be configured as an A record for this FQDN in the DNS server within the AP's domain, enabling successful AP joining.

`ap-manager.domain.com` is not the standard FQDN used for CAPWAP controller discovery; the AP manager interface is an internal WLC interface.

`primary-wlc.domain.com` is a generic hostname and not the specific FQDN that Cisco APs are configured to resolve for WLC discovery.