Nslookup and fully qualified name

phn at icke-reklam.ipsec.nu phn at icke-reklam.ipsec.nu
Sat Jan 24 10:58:42 UTC 2004

Stephane Bortzmeyer <bortzmeyer at nic.fr> wrote:
> On Fri, Jan 23, 2004 at 06:34:15PM +0000,
>  phn at icke-reklam.ipsec.nu <phn at icke-reklam.ipsec.nu> wrote 
>  a message of 31 lines which said:

>> The format of the domain name, it's illegal 

> As a domain name, it is certainly LEGAL. As an host name, it WAS
> illegal but it is no longer.

>> See rfc1123 for details  

> On the contrary, RFC 1123 was the one which authorized all-digits
> names (before RFC 1123, you needed an initial letter).

> Read it: 2.1  "Host Names and Numbers", p.13

OK, i'll quote :
"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
And a littee later :
"If a dotted-decimal number can be entered without such
           identifying delimiters, then a full syntactic check must be
           made, because a segment of a host domain name is now allowed
           to begin with a digit and could legally be entirely numeric
           (see Section  However, a valid host name can never
           have the dotted-decimal form #.#.#.#, since at least the
           highest-level component label will be alphabetic."

I stand corrected.

I do however insist on the hazards involved with using all-numeric
host-names, they will trigger software anomalies everywhere.

Peter Håkanson         
        IPSec  Sverige      ( At Gothenburg Riverside )
           Sorry about my e-mail address, but i'm trying to keep spam out,
	   remove "icke-reklam" if you feel for mailing me. Thanx.

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