Question about recursion queries

[Lyle Giese]

Recursive queries start with the root name servers.  That list is built
in to almost(I am reluctant to say all) all versions of bind and is
availible for download from ftp.rs.internic.net.

An unknown server is one that 1) does not answer queries or 2) has not
been asked yet by this bind server.  Over time, bind figures out which
of those servers answers fastest and will tend to ask the fast ones the
most questions.

Lyle Giese
LCR Computer Services, Inc.

Zhang Meng wrote:
> Thanks for your information.
>
> But what does unknown servers mean? Where does the list come from?
>
>
>
> On Tue, Jul 20, 2010 at 7:08 AM, Chris Buxton
> <chris.p.buxton at gmail.com <mailto:chris.p.buxton at gmail.com>> wrote:
>
>     It uses the RTT algorithm to select the "fastest" server from the
>     list, using random, low values for unknown servers. ("Fastest" is
>     in quotes because the algorithm does not do exactly that, but it's
>     close.)
>
>     No, I cannot show you the code. I'm not a developer. Find it yourself.
>
>     Regards,
>     Chris Buxton
>     BlueCat Networks
>
>     On Jul 19, 2010, at 2:12 AM, Zhang Meng wrote:
>
>>
>>     The question is given that
>>
>>     When I ask the bind server, what's the A record of google.com
>>     <http://google.com/>?
>>
>>     for the ROOT name server, there're several NS record
>>
>>     /.// //60493// //IN// //NS// //g.root-servers.net
>>     <http://g.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //b.root-servers.net
>>     <http://b.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //m.root-servers.net
>>     <http://m.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //d.root-servers.net
>>     <http://d.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //j.root-servers.net
>>     <http://j.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //c.root-servers.net
>>     <http://c.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //i.root-servers.net
>>     <http://i.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //a.root-servers.net
>>     <http://a.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //h.root-servers.net
>>     <http://h.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //k.root-servers.net
>>     <http://k.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //l.root-servers.net
>>     <http://l.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //f.root-servers.net
>>     <http://f.root-servers.net/>./
>>     /.// //60493// //IN// //NS// //e.root-servers.net
>>     <http://e.root-servers.net/>./
>>
>>     How does the bind handle these multiple NS records?
>>
>>     A).Select one of them to ask the NS records for com. ? If fails,
>>     try the second one?
>>     B).Or send several queries concurrently, and get the first one
>>     responsed?
>>
>>
>>     Could you show me the related code in Bind9.7.1-P2?
>>
>>     -- 
>>     Yours sincerely
>>     ZhangMeng
>>     _______________________________________________
>>     bind-users mailing list
>>     bind-users at lists.isc.org <mailto:bind-users at lists.isc.org>
>>     https://lists.isc.org/mailman/listinfo/bind-users
>
>
>
>
> -- 
> Yours sincerely
> ZhangMeng
> ------------------------------------------------------------------------
>
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