I have one domain xyz.com but it is a subdomain of abc.com (xyz.abc.com). I have installed a SSL certificate for xyz.com but it doesn't work.

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Should I buy another SSL certificate for xyz.abc.com or one for abc.com?

2 Answers 2


You should buy a certificate that covers whatever your users will type into their browsers, and whatever there are internal links to. It might be cheaper to experiment with self-signed certificates until you are clear what is needed.

There may be a problem if you do not own abc.com, as the CA will not issue a certificate (as that is rather the point: imagine that abc.com is your bank, and fraudsters are trying to buy certificates for subdomains of your bank).

When you say the certificate does not work, it should warn users this is not xyz.com, and encrypt traffic if users click through anyway. That means the certificate works. If nothing at all happens, you have not installed it correctly.

  • Thee user are going to type "(www.)xyz.com" and the certificate was applied to that domain. Maybe it was installed wrong, or the CSR wasn't generated properly (it was rejected 3 times because of the country code: "PE"). We own abc.com. Also, there is no warning message, just it is not working. I will contact (again) the hosting provider who sell us the certificate. Thanks for your help. May 22, 2012 at 2:53

Yes, you should obtain another certificate for your subdomain xyz.

the issued certificate is for abc.com so it won't work on any other subdomain.

Users will get a warning message while opening https://xyz.abc.com saying that the Certificate not Trusted, or the certificate has been issued to other domain name.

So you bind different certificate to different site names.

  • The issued certificate is for xyz.com. We generated the CSR for that domain and then we send it to the hosting provider. There is no warning message so it's 100% sure that it wasn't installed properly. xyz is a subdomain of abc; but it is also domain. May 22, 2012 at 2:55

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