I am trying to figure out whether I need a new internal IP, external IP or both to configure an IIS 7.5 server to run with two secure sub domains each using a different SSL cert, with both domains using port 443.

I have IIS 7.5 configured to route traffic properly to both domains (by adding a wildcard to the friendly SSL cert name so I can enable host headers over HTTPS) but the second secure domain is still trying to use the first domains SSL cert.

After researching I learned that I cannot have both domains running on the same IP address, using the same port, while having different SSL certificates. I have read that I can make it work by adding a second IP address to the server and assigning the domains to the different IP addresses.

The setup I want to have on the same IIS 7.5 server is this:

secure1.mydomain.com, Port 443, SSL Cert1

secure2.mydomain.com, Port 443, SSL Cert2

My question, is whether I need a new internal IP, or external IP, or do I need both to make this configuration work? I would rather not have to use a Wildcard Cert that houses both subdomains, because I have already purchased the individual Certs for the subdomains.

Thanks in advance.


If you want to publish your subdomains on the internet, both of them on default port 443, you definitely need 2 public IP addresses.

SSL Certs apply to the connection, before the client can HTTP-request one of the configured domain on your server, so basically you need one cert for each IP+PORT combination.

With single domain SSL cert, vhosting cannot be done.

  • Thanks for the response. I did indeed need a new external ip address to get both secure sub-domains working on the same IIS server, but I also needed a 2nd internal IP address to tie to the external address. So for any else trying to do the same thing I was doing, you will need a new IP pair both external and internal.
    – jjspierx
    Jan 14 '14 at 4:01

See my comment above to nrc's answer. To make the above configuration work, an IP pair is required, both internal and external IP's if you are using individual SSL certs to host two secure HTTPS sites on the same IIS 7.5 server using port 443.

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