DNS – How to Point Domain to Different Server Without Changing Nameservers

In this case you would need separate ports if they were on the same IP, or separate IPs if you wanted them on the same standard SSL port (443). IIS doesn't support reading host headers and redirecting using SSL. You can use the same wildcard certificate without any issue, but you would need something inbetween IIS and the client (like Microsoft Forefront Threat Management Gateway) in order to do routing by hostname over SSL. (I hope that makes sense)

The reason this happens is because the connection is encrypted and the certificate is validated before the HTTP header is actually sent, so at that time IIS has to know what site it's using beforehand. Now, Firefox does send the hostname in with the initial encryption request but I'm not sure if IIS supports that (or if any other browsers do).

The First Few Milliseconds of a HTTPS Connection has an incredibly in depth description on how HTTPS generally works (through a special debug build of Firefox). As you can see a few paragraphs in TLS supports a server name extension, but as far as I know IIS does not support that extension.

You need a NS record that lists the hostname of your server (this defines it as a DNS name server) and you need an A record that matches that hostname to your external IP address. You then need to tell your domain registar to point to this hostname for DNS. That will get you started and then you're free to create other DNS records on your server as you wish.