Wildcard SSL Certificate can secure multiple Fully Qualified Domain Names if they share the same base domain name and share the same second level domain name.
Secure Multiple Subdomains with one certificate
Secure Multiple Sub-Domains with a Single Symantec Wildcard SSL Certificate
Secure multiple sub-domains on different servers with one certificateSave Save Save Save Save Save Save Save Save
Secure multiple subdomains with a single certificate in just minutes