How to add SSL to subdomain that points to a different server?

I've got a webserver that has a single domain SSL certificate: https://secure.example.com

I also have a couple of subdomains 开发者_运维知识库that point to different servers:

• http://www.example.com, which points to the main server.
• http://subdomain.example.com which points to a completely different server.

What is the best way to add SSL to the subdomain https://subdomain.example.com

Is it possible to configure something like this with a wildcard certificate? Or is it better to purchase another single-domain certificate and install it on the seperate server?

You can get a wildcard cert but that is probably more expensive than you need and you'd need to copy your private key to each server -- which really is not recommended unless you are a crypto expert. You are better off simply purchasing two more certs for the two additional machines.

Wild card certificates only cover domains on the same server. I believe it's because the key used in the certificate is tied back to the server.

If you want to add a certificate for sites on other servers you will need specific certificates for those server/domain combinations.