Like its predecessors, IIS7 does not support wildcard (catch-all) binding or wildcards for host names, see this discussion for the state of things and how the much requested feature didn’t make it into the II7 release version as it stands. So, if you try to add *.yourdomain.com as a host name in IIS 7 you will get this warning:
There is only one “workaround” at the web server level and it requires a dedicated IP address for the particular site:
Set up a wildcard host record in DNS: right-click the zone yourdomain.com in DNS Manager>>New Host (A or AAAA)>>enter asterisk as wildcard and the dedicated IP address:
Then create you site in IIS without any host name:
This way DNS effectively takes care of the mapping of the URLs, throwing everything at the bound IP address which is pointing to your site. Here’s hoping that IIS will someday catch up with Apache and allow more flexible wildcard mapping of host names.