Question

Say I have the following domain:

example.com

I have a Wildcard SSL certificate for this domain. Subdomains like test.example.com validate properly. However, when I try to use a domain like demo.test.example.com, I get an error message in all major browsers:

demo.test.example.com uses an invalid security certificate.

The certificate is only valid for the following names:
  *.example.com , example.com

Is it possible to use a wildcard certificate for a “sub-subdomain”?

Answer 1

Well, you’ve already verified that you can’t! Here’s why:

From: http://www.ietf.org/rfc/rfc2818.txt

Names may contain the wildcard character * which is considered to
match any single domain name
component or component fragment. E.g.,
*.a.com matches foo.a.com but not bar.foo.a.com. f*.com matches foo.com
but not bar.com.