 For each zone, the DNS service may choose to perform full resolution (normal behaviour), or other actions, including declaring that the requested domain does not exist (technically, NXDOMAIN), or that the user should visit a different domain (technically, CNAME), amongst other potential actions.As zone information can be obtained from external sources (via a zone transfer) this allows a DNS service to obtain information from an external organisation about domain information and then choose to handle that information in a non-standard manner.RPZ is essentially a filtering mechanism, either preventing people from visiting internet domains, or pointing them to other locations by manipulating the DNS answers in different ways.