I have 2 web servers in Azure (prod and test).

I have created (temporarily) a self signed certificate (using IIS) on both.

One certificate works fine, but the other is causing downloads to fail because of "certificate errors".

One server is for prod.mysite.com, the other is for test.mysite.com.

Is there something about these certificates that will be preventing me from using two servers for the same domain (although different subdomain) that I don't know about.

I just can't work out why one works and the other doesn't.

The certificates look the same (except the server name).



If your server uses one IP address for both subdomains, IIS setup for (for the second and any additional certificates) requires the Server Name Indication (SNI) feature. For any request, SNI permits the binding of the SSL certificate to use the hostname rather than the IP address.

When adding server certificates in IIS manager, in the "Add Site Binding" dialog check the SNI checkbox for the second (and any additional) certificate(s).

For more details see install multiple SSL certificate on Microsoft IIS.

| improve this answer | |
  • Yes, I am familiar with this. There are actually multiple sites on each server. The domains I listed above are actually a simplified example. – Beakie Jul 27 '19 at 18:32

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