This test will list SRV records for a domain. The DNS lookup is done directly against the domain's authoritative name server, so changes to DNS Records should show up instantly. SRV Records are used to provide information about available services available for a domain. The naming system is an underscore followed by the name of the service, followed by a period, and underscore, and then the protocol, another period, and then the name of the domain. Example _http._tcp.mxtoolbox.com