Domain Name System Message Format. All three message formats can be sent using TNEF. Note that the contents of the answer section may have multiple owner names because of aliases.
Other rules include not starting or ending labels with hyphens and not having a fully numeric top-level domain name. By looking up a destination servers address in the DNS the sending server can properly route a message to a recipient. Domain names must mot have more than 63 characters.
DNS uses TCP for bigger exchange ie.
DNS is a directory service that provides a mapping between the name of a host on the network and its numerical address. The total domain character length can have up to 253 characters. DNS Messages Frame Format. The response message consisits of a header question records answer records authoritative records and additional records.