There are two ways to see which Certificate Authority servers exist in your AD domain.
The AD group Cert Publishers contain the servers that are permitted to publish certificates to AD. As a consequence, this gruop will contain all servers that are CAs.
You can use the certutil command to view (and select from) a list of CAs in the current AD domain:
certutil -config - -ping
Note: type the command as-is, including all spaces and hyphens.
A window will appear, listing the CA name and the server it runs on.