<div dir="ltr"><div dir="ltr"><div class="gmail_default" style="font-family:verdana,sans-serif"><br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Wed, Mar 18, 2020 at 9:03 AM Purva Rawan <<a href="mailto:purvar@cdac.in">purvar@cdac.in</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
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<p>Hello ,</p>
<p><span style="font-size:9pt">We have configured splitDNS .Bind version is 9.9.2.We are able to lookup and browse to particular URL( e.g.</span><a href="https://registry.npmjs.org/" target="_blank">https://registry.npmjs.org</a><span style="font-size:9pt">) from internal network but the same URL when we tried from external network ,it failed to browse ,but able to do nslookup.We checked tcpdump logs and observed that DNS protocol switched from udp to tcp.</span></p>
<p><span style="font-size:9pt">Tcpdump logs for reference</span></p>
<p><span style="font-size:9pt">17:39:28.380918 ARP, Request who-has 196.1.113.242 tell 196.1.113.248, length 28</span></p>
<p>17:39:28.381205 ARP, Reply 196.1.113.242 is-at 00:09:0f:09:00:1a, length 46</p>
<p>17:39:30.395995 IP 196.1.113.242.54930 > 196.1.113.248.domain: Flags [S], seq 2177054283, win 14600, options [mss 1460,sackOK,TS val 2512104 ecr 0,nop,wscale 7], length 0</p>
<p>17:39:38.420575 IP 196.1.113.242.54930 > 196.1.113.248.domain: Flags [S], seq 2177054283, win 14600, options [mss 1460,sackOK,TS val 2520128 ecr 0,nop,wscale 7], length 0</p>
<p>17:39:54.451991 IP 196.1.113.242.54930 > 196.1.113.248.domain: Flags [S], seq 2177054283, win 14600, options [mss 1460,sackOK,TS val 2536160 ecr 0,nop,wscale 7], length 0</p>
<p>17:40:26.483591 IP 196.1.113.242.54930 > 196.1.113.248.domain: Flags [S], seq 2177054283, win 14600, options [mss 1460,sackOK,TS val 2568192 ecr 0,nop,wscale 7], length 0<span style="font-size:9pt"> </span></p>
<p>Kindly help to resolve the same.</p></div></blockquote><div><div class="gmail_default" style="font-family:verdana,sans-serif">You appear to have network / firewall, not DNS issues -- 196.1.113.242 is sending SYN (open a connection) packets to <a href="http://ns1.cdac.in">ns1.cdac.in</a>, but is not getting any reply packets from it (assuming you included all of the tcpdump output) - this either means that <a href="http://ns1.cdac.in">ns1.cdac.in</a> was down, or, more likely, that 196.1.113.242 cannot send packets to it on port 53. </div><div class="gmail_default" style="font-family:verdana,sans-serif">As a quick and dirty test, can you telnet from 196.1.113.242 to port 53 on 196.1.113.248? </div><div class="gmail_default" style="font-family:verdana,sans-serif"><br></div><div class="gmail_default" style="font-family:verdana,sans-serif">W</div><br></div><div><br></div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div>
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Regards,
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Purva Rawan
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</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature">I don't think the execution is relevant when it was obviously a bad idea in the first place.<br>This is like putting rabid weasels in your pants, and later expressing regret at having chosen those particular rabid weasels and that pair of pants.<br> ---maf</div></div>