The encoding of any identifier used as part of a Fully Qualifed Domain Name (FQDN) shall follow the Name Syntax
defined in RFC 2181, RFC 1035 and RFC 1123. An FQDN consists of one or more
labels. Each label is coded as a one octet length field followed by that number of octets coded as 8 bit ASCII characters.
Following RFC 1035 the labels shall consist only of the alphabetic characters (A-Z and a-z), digits (0-9) and
the hyphen (-).
Following RFC 1123, the label shall begin and end with either an alphabetic character or a
digit. The case of alphabetic characters is not significant. Identifiers are not terminated by a length byte of zero.