Positive SSL Wildcard is a cost-effective solution for protecting a large number of subdomains. This certificate can be issued for an unlimited number of first-level subdomains. It is easy to install, so it will save you time and effort. For example, if a PositiveSSL Wildcard SSL cerificate has been issued for yourdomain.com, it is also valid for www.yourdomain.com, secure.yourdomain.com, mail.yourdomain.com, etc. Please note that this cerificate doesn't cover fourth-level subdomains and beyond, like www.secure.yourdomain.com or dev.secure.yourdomain.com.
Additional description:
One certificate protects lots of subdomains.
• It's a domain-validated certificate.
• It protects all popular browsers.
• It is compatible with 99.9% of the browser types.
• It can be used with mail and web servers.
• It can be reissued an unlimited number of times.