<html><head></head><body><div style="color:#000; background-color:#fff; font-family:Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div id="yui_3_16_0_ym19_1_1495060579056_3944"><span id="yui_3_16_0_ym19_1_1495060579056_3943">So if the limit is set to unlimited, bind still only recurses once for the same lookups, correct?</span></div><div class="qtdSeparateBR" id="yui_3_16_0_ym19_1_1495060579056_3942"><br><br></div><div class="yahoo_quoted" id="yui_3_16_0_ym19_1_1495060579056_3810" style="display: block;">  <div style="font-family: Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1495060579056_3809"> <div style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;" id="yui_3_16_0_ym19_1_1495060579056_3808"> <div dir="ltr" id="yui_3_16_0_ym19_1_1495060579056_3807"> <font size="2" face="Arial" id="yui_3_16_0_ym19_1_1495060579056_3806"> <hr size="1" id="yui_3_16_0_ym19_1_1495060579056_3951"> <b><span style="font-weight:bold;">From:</span></b> Mark Andrews <marka@isc.org><br> <b><span style="font-weight: bold;">To:</span></b> Shawn Zhou <shawnzhou00@yahoo.com> <br><b><span style="font-weight: bold;">Cc:</span></b> Evan Hunt <each@isc.org>; "dns-operations@lists.dns-oarc.net" <dns-operations@dns-oarc.net><br> <b><span style="font-weight: bold;">Sent:</span></b> Tuesday, April 4, 2017 11:52 AM<br> <b><span style="font-weight: bold;">Subject:</span></b> Re: [dns-operations] max-clients-per-query limit<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_ym19_1_1495060579056_3812"><br><div dir="ltr" id="yui_3_16_0_ym19_1_1495060579056_3811"><br clear="none">In message <<a shape="rect" ymailto="mailto:317795614.485739.1491329002484@mail.yahoo.com" href="mailto:317795614.485739.1491329002484@mail.yahoo.com" id="yui_3_16_0_ym19_1_1495060579056_3952">317795614.485739.1491329002484@mail.yahoo.com</a>>, Shawn Zhou writes:<br clear="none">><br clear="none">> Hi Evan,<br clear="none">> How long is the time window that BIND uses to calculate the identical<br clear="none">> lookups? Is it over 1-minute window? or 5-minute window?<br clear="none">><br clear="none">> Thanks,Shawn<br clear="none"><br clear="none">Whenever named recurses it looks to see if there is a existing<br clear="none">client already recursing for the given <QNAME,QTYPE,QCLASS>.  If<br clear="none">there is the client attaches itself to the lookup and waits for it<br clear="none">to resolve.  If there are already too many clients waiting for that<br clear="none">lookup to complete it drops the client which should retry a short<br clear="none">while later, when, hopefully the lookup has succeeded and the query<br clear="none">can be answered from the cache.<div class="yqt7727637580" id="yqtfd48493"><br clear="none"><br clear="none">>       From: Evan Hunt <<a shape="rect" ymailto="mailto:each@isc.org" href="mailto:each@isc.org">each@isc.org</a>><br clear="none">>  To: Shawn Zhou <<a shape="rect" ymailto="mailto:shawnzhou00@yahoo.com" href="mailto:shawnzhou00@yahoo.com">shawnzhou00@yahoo.com</a>><br clear="none">> Cc: "<a shape="rect" ymailto="mailto:dns-operations@lists.dns-oarc.net" href="mailto:dns-operations@lists.dns-oarc.net">dns-operations@lists.dns-oarc.net</a>" <<a shape="rect" ymailto="mailto:dns-operations@dns-oarc.net" href="mailto:dns-operations@dns-oarc.net">dns-operations@dns-oarc.net</a>><br clear="none">>  Sent: Wednesday, March 22, 2017 10:07 PM<br clear="none">>  Subject: Re: [dns-operations] max-clients-per-query limit<br clear="none">><br clear="none">> On Wed, Mar 22, 2017 at 10:05:35PM +0000, Shawn Zhou wrote:<br clear="none">> > What happens when max-clients-per-query is reached? say, we have 120<br clear="none">> > duplicate requests and the max-clients-per-query is set to 100. Do<br clear="none">> > the 20 "extra" requests got dropped or get timeouts or they will be<br clear="none">> > part of next grouped requests?<br clear="none">><br clear="none">> They're dropped.<br clear="none">><br clear="none">> --<br clear="none">> Evan Hunt -- <a shape="rect" ymailto="mailto:each@isc.org" href="mailto:each@isc.org" id="yui_3_16_0_ym19_1_1495060579056_3953">each@isc.org</a><br clear="none">> Internet Systems Consortium, Inc.</div><br clear="none"><br clear="none">-- <br clear="none">Mark Andrews, ISC<br clear="none">1 Seymour St., Dundas Valley, NSW 2117, Australia<br clear="none">PHONE: +61 2 9871 4742                 INTERNET: <a shape="rect" ymailto="mailto:marka@isc.org" href="mailto:marka@isc.org">marka@isc.org</a><div class="yqt7727637580" id="yqtfd66032"><br clear="none"></div></div><br><br></div> </div> </div>  </div></div></body></html>