Wildcard SSL certificates secures your website URL and an unlimited number of its subdomains. For example, a single Wildcard certificate can secure www.coolexample.com, blog.coolexample.com, and store.coolexample.com.
Wildcard certificates secure the common name and all subdomains at the level you specify when you submit your request. Just add an asterisk (*) in the subdomain area to the left of the common name.
If you request your certificate for *.coolexample.com, you can secure:
If you request your certificate for *.www.coolexample.com, you can secure:
Wildcard certificates secure websites just like regular SSL certificates, and requests are processed using the same validation methods. However, some Web servers might require a unique IP address for each subdomain on the Wildcard certificate.