root server query question

[Mark de Vries]

On Thu, 28 Apr 2005 Christopher.Lee at uboc.com wrote:

>
> Hello,
>
> Thanks.  Should have known to look in CPAN you can find everything there.
> I already have a simple script working.  :-)
>
> One question about how this works behind the screen.  I just want to make
> sure it is doing this correctly...
>
> If I do a query to get the NS records like so:
>
> use Net::DNS;
> my $res   = Net::DNS::Resolver->new(Verbose => 1);
> my $query = $res->query("uboc.com", "NS");
>
> if ($query) {
>     foreach $rr (grep { $_->type eq 'NS' } $query->answer) {
>         print $rr->nsdname, "\n";
>     }
> } else {
>     warn "query failed: ", $res->errorstring, "\n";
> }
>
> It appears that it is getting this information from my name servers and not
> from the root servers because I know we have some differences right now

Yes, unless you tell it to do otherwise, it's using whatever you have in
/etc/resolv.conf.

When writing a script to solve the same problem once I just got a list of
root servers from the default ones (resolv.conf) and then just do the
iterative process (from root down) 'manually' in the script.

I tried to find the code but failed so I can't send it to you :(

I do remeber one little 'gotcha'; some server returned the info I needed
in the answer section, others in the auth section. Remember to look at
both when checking if your query returned any 'answers'.

Good luck,
Mark.