Hostname verification is a little known part of HTTPS that involves a server identity check to ensure that the client is talking to the correct server and has not been redirected by a man in the middle attack.
The check involves looking at the certificate sent by the server, and verifying that the
dnsName in the
subjectAltName field of the certificate matches the host portion of the URL used to make the request.
WS SSL does hostname verification automatically.
Hostname Verification can be tested using
dnschef. A complete guide is out of scope of documentation, but an example can be found in Testing Hostname Verification.