NAPTR-Pattern is an optional parameter that specifies a regexp that will be used to match the contents of NAPTR records during Resolver service discovery.

If NAPTR-Pattern is defined and matches a NAPTR DNS record, it will be used to determine the protocol and transport to be used. The regexp is expected to match 2 substrings. The first is the protocol and can be 'radsec' or 'radius'. The second is the transport to use, and can be 'tls', 'tcp' or 'udp'.