<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><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>On Jul 19, 2010, at 2:12 AM, Zhang Meng wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><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 href="http://google.com/">google.com</a>?</div><div><br></div>for the ROOT name server, there're several NS record<div>
<br><div><div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://g.root-servers.net/">g.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://b.root-servers.net/">b.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://m.root-servers.net/">m.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://d.root-servers.net/">d.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://j.root-servers.net/">j.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://c.root-servers.net/">c.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://i.root-servers.net/">i.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://a.root-servers.net/">a.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://h.root-servers.net/">h.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://k.root-servers.net/">k.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://l.root-servers.net/">l.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://f.root-servers.net/">f.root-servers.net</a>.</i></div>
<div><i>.</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>60493</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>IN</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i>NS</i><span class="Apple-tab-span" style="white-space:pre"><i> </i></span><i><a href="http://e.root-servers.net/">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>
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