What is the significance of this tag in the WCF client config? What does it actually mean. I have seen people put the name of their certificates in this tag like
<dns value="CertificateName">
Can any WCF experts out there give me a detailed explanation...
I am assuming that the dns tag is the client -> endpoint -> indentity -> dns tag.
In that case the value is the name of the server that the client expects to be talking to.
http://msdn.microsoft.com/en-us/library/ms733130.aspx
If you want to use a certificate to identify the service you would use the certificate tag or the rsa tag.
The service is identifying itself by means of a certificate installed on the machine where your service is running.
The <dns> tag defines what the "subject name" (or identity) of that service certificate is going to be, so that the client can check to see whether the certificate presented by the service to "prove" its identity is really what it expected it to be.
There's a really good set of blog post here that talk about WCF security scenarios - one of them (part 4) is Internet scenario which mentions the service authenticating itself by means of a certificate as well.
Hope this helps a bit
Marc