What is a wildcard domain name?
A wildcard domain name matches any first level subdomain or hostname in a domain. A first-level subdomain is a single domain name label that does not contain a period (dot). For example, you can use the name *.example.com to protect www.example.com, images.example.com, and any other host name or first-level subdomain that ends with .example.com. Learn more in the ACM User Guide.