Which certificate contains an asterisk in its domain name field, allowing usage for any number of subdomains?

The correct answer is C, as a wildcard certificate is specifically designed to secure an unlimited number of subdomains within a single domain. The asterisk (*) in the domain name field of a wildcard certificate indicates that it can be used for any subdomain. For example, if you have a wildcard certificate for *.example.com, it would cover subdomains such as mail.example.com, www.example.com, and anything else that falls under example.com.

Wildcard certificates are particularly useful for organizations with several subdomains, as they simplify management by allowing a single certificate to cover all of them, thereby making renewal and issuance less cumbersome.

In contrast, Extended Validation (EV) certificates, General purpose certificates, and Domain Validation (DV) certificates do not offer this expansive coverage. EV certificates provide a higher level of validation and are used to boost trust on websites, but they do not inherently cover multiple subdomains as a wildcard does. General purpose certificates typically secure a specific domain but do not allow wildcard coverage, and DV certificates confirm that the applicant has control over a domain but are also limited to that specific domain or subdomains specified without the wildcard capability.