In the IIS configurations there is a section to configure which address are allowed to access the web-site in term of host-names.
For example, we can access our application in several ways:
We can configure this in the IIS for our web-site:
On IIS 6:
right click on the web-site->properties-> web-site tab –> advanced
On IIS 7 and up:
right click on the web-site –> Edit bindings
*on IIS 7 on windows 7, as you can see the configuration is for all kinds of bindings, not just http.
The default is an empty host name => you can access any way you want. but you can set all kinds of host-names for all kind of ports. this way you are limiting the access to your site, and of course this is the best-practice for securing your site. usually we will configure our server-name and our load balancer server if we have one.
So what does WCF has to do with all of that??
Well, when you configure more that one host-name to a specific binding(let's say http) on your IIS and try to access a service on the site via that binding you'll get not-so-nice error that says that you have too many http-address but you only allowed to have one:
"This collection already contains an address with scheme http. There can be at most one address per scheme in this collection."
The solution is quiet simple – you can set an address filter in the server config that tells him to access the server with a specific address only. you can do this with baseAddressPrefixFilter: