Which DNS record type is required to allow APs to discover a WLC by using DNS on IPv4?

An NS record (Name Server record) specifies the authoritative DNS servers for a domain, not an IP address for a host.

An A record (Address record) in DNS is used to map a hostname to an IPv4 address. APs configured for DNS-based WLC discovery query for a specific hostname (e.g., 'cisco-capwap-controller') and expect an A record to return the WLC's IPv4 address.

An SOA record (Start of Authority record) provides administrative information about a DNS zone, such as the primary name server and zone administrator.

An MX record (Mail Exchanger record) specifies mail servers responsible for accepting email messages on behalf of a recipient's domain, not a WLC's IP address.