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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 <a class="moz-txt-link-abbreviated" href="ftp://ftp.rs.internic.net">ftp.rs.internic.net</a>.<br>
<br>
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.<br>
<br>
Lyle Giese<br>
LCR Computer Services, Inc.<br>
<br>
Zhang Meng wrote:
<blockquote
cite="mid:AANLkTinKYxIIbQAIqZ538s3i5XqIdAshS15TQfRPCeFs@mail.gmail.com"
type="cite">
<div>Thanks for your information.</div>
<div><br>
</div>
But what does unknown servers mean? Where does the list come from?
<div><br>
</div>
<div><br>
</div>
<div><br>
<div class="gmail_quote">On Tue, Jul 20, 2010 at 7:08 AM, Chris
Buxton <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:chris.p.buxton@gmail.com">chris.p.buxton@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote"
style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<div style="">
<div>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.)</div>
<div><br>
</div>
<div>No, I cannot show you the code. I'm not a developer. Find it
yourself.</div>
<div><br>
</div>
<div>Regards,</div>
<div>Chris Buxton</div>
<div>BlueCat Networks</div>
<br>
<div>
<div>
<div class="h5">
<div>On Jul 19, 2010, at 2:12 AM, Zhang Meng wrote:</div>
<br>
</div>
</div>
<blockquote type="cite">
<div>
<div class="h5">
<div><br>
</div>
<div>The question is given that</div>
<div><br>
</div>
<div>When I ask the bind server, what's the A record of <a
moz-do-not-send="true" href="http://google.com/" target="_blank">google.com</a>?</div>
<div><br>
</div>
for the ROOT name server, there're several NS record
<div><br>
<div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://g.root-servers.net/" target="_blank">g.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://b.root-servers.net/" target="_blank">b.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://m.root-servers.net/" target="_blank">m.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://d.root-servers.net/" target="_blank">d.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://j.root-servers.net/" target="_blank">j.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://c.root-servers.net/" target="_blank">c.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://i.root-servers.net/" target="_blank">i.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://a.root-servers.net/" target="_blank">a.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://h.root-servers.net/" target="_blank">h.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://k.root-servers.net/" target="_blank">k.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://l.root-servers.net/" target="_blank">l.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://f.root-servers.net/" target="_blank">f.root-servers.net</a>.</i></div>
<div><i>.</i><span style=""><i> </i></span><i>60493</i><span
style=""><i> </i></span><i>IN</i><span style=""><i> </i></span><i>NS</i><span
style=""><i> </i></span><i><a moz-do-not-send="true"
href="http://e.root-servers.net/" target="_blank">e.root-servers.net</a>.</i></div>
</div>
<div><br>
</div>
<div>How does the bind handle these multiple NS records?<br>
<div>
<div><br>
</div>
<div>A).Select one of them to ask the NS records for com. ? If
fails, try the second one?</div>
<div>B).Or send several queries concurrently, and get the first
one responsed?</div>
<div><br>
</div>
<div><br>
</div>
<div>Could you show me the related code in Bind9.7.1-P2?<br
clear="all">
<br>
-- <br>
Yours sincerely<br>
ZhangMeng<br>
</div>
</div>
</div>
</div>
</div>
</div>
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<br>
</div>
</blockquote>
</div>
<br>
<br clear="all">
<br>
-- <br>
Yours sincerely<br>
ZhangMeng<br>
</div>
<pre wrap="">
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