Domain Name Valid Characters Rfc

A subset of those strings use native character labels that require idna2003 mapping to produce valid a labels.

Domain name valid characters rfc. Label is the part of a domain name in between dots. Master files are text files that are read by a local name server and hence become available through the name servers to users of the domain system. That one restriction relates to the length of the label and the full name. Although it would be possible to provide a flat space or a name space in which for example the last label of a domain name captured the old style network name any such approach would add complexity to the method and create different rules for network names and host names.

If you are interested in reading all the finer details of a particular character then skip to the last to see the table of all the characters that you can or cannot include in your domain name. Hostname is a special type of domain name which identifies internet hosts. Domain name is the identifier of a resource in a dns database. These master files are updated by local system administrators.

A note on terminology in furtherance to bortzmeyer s answer. The length of any one label is limited to between 1 and 63 octets. The hostname is subject to the restrictions of rfc 952 and the slight relaxation of rfc 1123. Rfc 1034 domain concepts and facilities november 1987 the domain system assumes that all data originates in master files scattered through the hosts that use the domain system.

The dns itself places only one restriction on the particular labels that can be used to identify resource records. 33 35 character string 35 domain name 34 35 35 a 12 byte order 8 ch 13 character case 9 class 11 cname 12 completion 42 cs 13 hesiod 13 hinfo 12 hs 13 in 13 in addr arpa domain 22 inverse queries 40 mailbox names 47 mb 12 md 12 mf 12 mg 12 minfo 12 minimum 20. Internationalized domain names which are encoded to comply with the requirements for a hostname allow for presentation of non ascii domains. Rfc 1101 dns encoding of network names and other types april 1989 network names.

List of valid domain name characters that you can have. In some situations warnings to the user or. I have detailed out below all the valid and invalid characters that a domain name can contain. It seems rfc 2181 removes the restrictions of rfc 1034 1123 which says that only letters digits and hyphen are allowed.

In mail systems compliant with rfc 6531 and rfc 6532 an email address may be encoded as utf 8 both a local part as well as a domain name. I have seen rfc 1034 1123 2181. One should be clear about definitions. Rfc 5890 idna definitions august 2010 domain name strings appear in native character form.