Dans la rfc en question :
```
2.1 Host Names and Numbers
The syntax of a legal Internet host name was specified in RFC-952
[DNS:4]. 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.
Et quand on va sur la RFC en question :
ASSUMPTIONS
A "name" (Net, Host, Gateway, or Domain name) is a text string up
to 24 characters drawn from the alphabet (A-Z), digits (0-9), minus
sign (-), and period (.). Note that periods are only allowed when
they serve to delimit components of "domain style names".
[^] # Re: Euh
Posté par totof2000 . En réponse au message Modifier ma zone DNS : avoir www.sous-domaine.org. Évalué à 4.
Bon, prenons le premier lien que tu as donné :
https://tools.ietf.org/html/rfc2181#section-11
Ceci nous renvoie à :
See also [RFC1123] section 6.1.3.5.
Dans la rfc en question :
```
2.1 Host Names and Numbers