... Apache HTTP Server Version 2.2 . ... If Apache requires DNS resolution to parse the configuration files then your server may be subject to reliability problems (ie. it might not boot), or denial and theft of service attacks (including users able to steal hits from other users). ... In order for Apache to function properly, it absolutely needs to have two pieces of information about each virtual host: the ServerName and at least one IP address that the server will bind and respond to. ...