As it stands now, your server will only handle forward resolution (converting names into addresses), but it is also sometimes necessary to convert addresses back into human readable names. In some situations an For public IP addresses only your ISP will can provide this service for you, but most organizations at least need to handle their . For private networks you can set it up for your own internal addressesorganisation. You also But even if you're setting up reverse DNS on the public internet - you need to understand what information the ISP would require.