one short question

[Brad Knowles]

At 4:20 PM -0400 6/1/01, Kevin Darcy wrote:

>  Nah, the IPv4 address space is only 2^32, so just do a reverse lookup of
>  every possible address and extract the RDATAs which happen to be in the
>  desired domain.

	Actually, IPv4 space is smaller than this.  You can ignore Class 
D (224.* and above), the RFC 1918 address spaces, and you should be 
able to get a list of what IP address spaces have not yet been 
assigned, and therefore don't need to be searched.

	However, this won't tell you all the CNAMEs, nor will it tell you 
all the alternative names that are directly resolved into A records 
themselves (but which may not be the canonical name for the 
machine/interface).

	And then there is the issue of IPv6 -- some people are already 
using it, so if you're going to start sweeping all IP space through 
reverse lookups, you'd also have to consider IPv6 as well.

>                   Much faster. And we all know that every A record has a
>  corresponding PTR, right? :-)

	Yeah, riiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiiight. ;-)

-- 
Brad Knowles, <brad.knowles at skynet.be>

/*        efdtt.c  Author:  Charles M. Hannum <root at ihack.net>          */
/*       Represented as 1045 digit prime number by Phil Carmody         */
/*     Prime as DNS cname chain by Roy Arends and Walter Belgers        */
/*                                                                      */
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/*   where title-key = "153 2 8 105 225" or other similar 5-byte key    */

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