IP addresses in NS records seem to be breaking hostname resolution

Mark_Andrews at isc.org Mark_Andrews at isc.org
Thu Jul 18 23:52:24 UTC 2002


> 
> 
> 
> > -----Original Message-----
> > From: bind-users-bounce at isc.org [mailto:bind-users-bounce at isc.org] On
> > Behalf Of Chris Davis
> > Sent: Wednesday, July 17, 2002 9:22 PM
> > To: bind-users at isc.org
> > Subject: RE: IP addresses in NS records seem to be breaking hostname
> > resolution
> > 
> > 
> > I'm afraid we have lost focus of the discussion.  The discussion
> regards
> > zones with NS records that incorrectly have RDATA using IP addresses
> > rather
> > than hostnames.  We are not addressing NS RDATA hostnames that do not
> seem
> > to resolve to an IP address.
> > 
> > The config that started our discussion was:
> > 
> > @	IN	NS 	209.44.8.1
> > @ 	IN	NS 	209.44.8.6
> > @	IN 	NS	216.90.116.7
> > 
> 
> Chris,  It is important to remember that *all numeric* hostnames are
> legal.  Hence, 209.44.8.1 is a perfectly legal hostname even though it
> does not end in a recognizable TLD.  It is not named's responsibility to
> ensure that the RDATA hostname is resolvable (for all the previously
> stated reasons).  If there was a TLD called "1", then we could have a
> host 209.44.8.1.  I forget the RFC, but, an RFC came out that removed
> the requirement for a domain name to begin with a letter (I think to
> accommodate companies like 3Com...)
> 
> Dave...
> 
> [clip...]
> 

	Actually 209.44.8.1 isn't a hostname.  Go read RFC 1123 again.
	I particular the last paragraph of the discussion.  The
	assumption here is that atleast one label will have a alpha.

	209.44.8.1.example.com is a hostname however.

	Note "0xdeadbeef" is not a good hostname because it is a IP
	address, see inet_aton().

	Mark

   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.

      Host software MUST handle host names of up to 63 characters and
      SHOULD handle host names of up to 255 characters.

      Whenever a user inputs the identity of an Internet host, it SHOULD
      be possible to enter either (1) a host domain name or (2) an IP
      address in dotted-decimal ("#.#.#.#") form.  The host SHOULD check
      the string syntactically for a dotted-decimal number before
      looking it up in the Domain Name System.

      DISCUSSION:
           This last requirement is not intended to specify the complete
           syntactic form for entering a dotted-decimal host number;
           that is considered to be a user-interface issue.  For
           example, a dotted-decimal number must be enclosed within
           "[ ]" brackets for SMTP mail (see Section 5.2.17).  This
           notation could be made universal within a host system,
           simplifying the syntactic checking for a dotted-decimal
           number.

           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 6.1.2.4).  However, a valid host name can never
           have the dotted-decimal form #.#.#.#, since at least the
           highest-level component label will be alphabetic.


--
Mark Andrews, Internet Software Consortium
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark.Andrews at isc.org


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