Just what *is* a hostname (rfc952/1123, etc)
Jim Reid
jim at rfc1035.com
Wed Jan 23 21:47:52 UTC 2002
>>>>> "David" == David Carmean <dlc-bu at halibut.com> writes:
David> It seems to be perfectly legal to create a domain named
David> "foo_b#r&.com.", if I'm reading RFC2181 correctly; the
David> question is whether the name of any node in the entire
David> subtree below that zone cut can be a legal Internet
David> hostname.
It can't. Valid hostnames can only be built from the characters
[a-zA-Z0-9-]. RFC1123 references RFC952 which could hardly be any
clearer about that:
1. 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".
RFC1123 relaxed the above rule to allow longer names (255 char limit)
and to permit a name (label) to start with a digit.
foo_b#r&.com is perfectly valid as a domain name of course. But not as
a hostname. Since foo_b#r&.com is not a valid hostname any names
within that domain can't be valid hostnames either.
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