A DN typically looks like CN=MyUser,CN=Users,DC=mydomain,DC=com although the exact sequence of tokens depends on the LDAP server configuration. It can be any valid DN as long as LDAP allows this user to query data.
This configuration is also useful when you are connecting to Active Directory from a Unix machine, as AD doesn't allow anonymous bind by default. But if you can't figure this out, you can also change AD setting to allow anonymous bind. See this document for how to.