<div>
hi, Aki tnuomi，
</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>Thank you for suggestion. I found pdns always get the fastest one from the front of result returned by function "SyncRes::shuffleInSpeedOrder”. If a slow one at the back has no opportunity to be choosed, how pdns know it become fast. I can not find the source code make pdns query the slow one. </div><div><br></div><div><span class="Apple-tab-span" style="white-space:pre"> </span>on the other hand, I found there is a houseKeeping thread which will erase the stale speed value of a dns server . If a slow dns at the back of t_sstorage->nsSpeeds map, it will be erased because of rarely to be queried, and only fast dns server will have its speed updated by this code "<span style="font-family: Monaco; font-size: 12px; color: rgb(149, 165, 167);"> t_sstorage</span><span style="font-family: Monaco; font-size: 12px; color: rgb(195, 153, 0);">-></span><span style="color: rgb(121, 158, 191); font-family: Monaco; font-size: 12px;">nsSpeeds</span><span style="font-family: Monaco; font-size: 12px; color: rgb(229, 73, 61);">[</span><span style="font-family: Monaco; font-size: 12px; color: rgb(195, 153, 0);">*</span><span style="font-family: Monaco; font-size: 12px; color: rgb(44, 158, 219);">tns</span><span style="font-family: Monaco; font-size: 12px; color: rgb(229, 73, 61);">]</span><span style="font-family: Monaco; font-size: 12px; color: rgb(195, 153, 0);">.</span><span style="color: rgb(121, 158, 191); font-family: Monaco; font-size: 12px;">submit</span><span style="font-family: Monaco; font-size: 12px; color: rgb(229, 73, 61);">(</span><span style="font-family: Monaco; font-size: 12px; color: rgb(195, 153, 0);">*</span><span style="font-family: Monaco; font-size: 12px; color: rgb(44, 158, 219);">remoteIP</span><span style="font-family: Monaco; font-size: 12px; color: rgb(195, 153, 0);">,</span><span style="font-family: Monaco; font-size: 12px; color: rgb(149, 165, 167);"> </span><span style="font-family: Monaco; font-size: 12px; color: rgb(44, 158, 219);">lwr</span><span style="font-family: Monaco; font-size: 12px; color: rgb(195, 153, 0);">.</span><span style="color: rgb(121, 158, 191); font-family: Monaco; font-size: 12px;">d_usec</span><span style="font-family: Monaco; font-size: 12px; color: rgb(195, 153, 0);">,</span><span style="font-family: Monaco; font-size: 12px; color: rgb(149, 165, 167);"> </span><span style="font-family: Monaco; font-size: 12px; color: rgb(195, 153, 0);">&</span><span style="color: rgb(121, 158, 191); font-family: Monaco; font-size: 12px;">d_now</span><span style="font-family: Monaco; font-size: 12px; color: rgb(229, 73, 61);">)</span><font color="#c39900" face="Monaco"><span style="font-size: 12px;">;” at syncres.cc:1003.</span></font></div><div>. And then, only dns servers which are mostly queried will stay in t_sstorage->nsSpeeds map. It make me puzzled.</div>
<div><div><br></div><div>-- </div><div>jacky</div><div><br></div></div>
<p style="color: #A0A0A8;">On Friday, December 27, 2013 at 3:08 PM, Aki Tuomi wrote:</p>
<blockquote type="cite" style="border-left-style:solid;border-width:1px;margin-left:0px;padding-left:10px;">
<span><div><div><div>On Thu, Dec 26, 2013 at 10:34:23PM +0800, jacky wrote:</div><blockquote type="cite"><div><div>hi, all, </div><div> I think may be it is a question more suitable to dev maillist, so I submit it here. If I made a mistake , please let me know. Thanks.</div><div> </div><div> I'am reading the source code of pdns-recursor-3.5.3. There is question I can not understand.</div><div> When a authoritative dns server become slow because of overload, pdns-recursor will move it backwards in the </div><div> t_sstorage->nsSpeeds map, and then a faster dns server will be used preferred. But when the dns server recoverd </div><div> from overload and become fast again, what will pdns-recursor do about it ? Will pdns-recursor move it forward </div><div> in speed map? I can't find relevant source code. Any suggestion?</div><div><br></div><div>-- </div><div>jacky</div></div></blockquote><div><br></div><div>Hi!</div><div><br></div><div>It works by moving the fastest one on top. </div><div><br></div><blockquote type="cite"><div><div>_______________________________________________</div><div>Pdns-dev mailing list</div><div><a href="mailto:Pdns-dev@mailman.powerdns.com">Pdns-dev@mailman.powerdns.com</a></div><div><a href="http://mailman.powerdns.com/mailman/listinfo/pdns-dev">http://mailman.powerdns.com/mailman/listinfo/pdns-dev</a></div></div></blockquote></div></div></span>
</blockquote>
<div>
<br>
</div>