One aspect of host name syntax is hereby changed: the restriction on the first character is relaxed to allow either a letter or a digit. Host software MUST sup

One aspect of host name syntax is hereby changed: the restriction on the first character is relaxed to allow either a letter or a digit. Host software MUST support this more liberal syntax. -- http://tools.ietf.org/html/rfc1123#section-2 http://tools.ietf.org/html/rfc1123#section-2