<div dir="ltr">We had a little mail outage which turned out to be caused by one of our caching DNS servers returning the bellow incomplete reply.<div><br></div><div>Clearing the cache on the problematic server fixed the issue.... </div>
<div><br></div><div>Am thinking it is now impossible for me to find the root cause in this instance... but wondering if you guys could hint at what could cause such a problem... bugs in the DNS servers involved? temporary misconfig at Google's servers? network issue?</div>
<div><br></div><div>The setup is a bit convoluted:</div><div><br></div><div>cache server --> resolver cache server --> Internet</div><div><br></div><div>The fix was clearing at the first server. so I am guessing at some point the resolver gave the incomplete answer.</div>
<div><br></div><div>Thanks a lot,</div><div>Mohamed.</div><div><br></div><div><div>➜ ~ dig <a href="http://mail.google.com">mail.google.com</a> @<a href="http://141.161.100.201">141.161.100.201</a></div><div><br></div>
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; <<>> DiG 9.9.5-3-Ubuntu <<>> <a href="http://mail.google.com">mail.google.com</a> @<a href="http://141.161.100.201">141.161.100.201</a></div><div>;; global options: +cmd</div><div>;; Got answer:</div>
<div>;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20414</div><div>;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 4, ADDITIONAL: 5</div><div><br></div><div>;; OPT PSEUDOSECTION:</div><div>; EDNS: version: 0, flags:; udp: 4096</div>
<div>;; QUESTION SECTION:</div><div>;<a href="http://mail.google.com">mail.google.com</a>.<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>A</div><div><br></div><div>;; ANSWER SECTION:</div>
<div><a href="http://mail.google.com">mail.google.com</a>.<span class="" style="white-space:pre"> </span>10213<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>CNAME<span class="" style="white-space:pre"> </span><a href="http://googlemail.l.google.com">googlemail.l.google.com</a>.</div>
<div><br></div><div>;; AUTHORITY SECTION:</div><div><a href="http://google.com">google.com</a>.<span class="" style="white-space:pre"> </span>96485<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>NS<span class="" style="white-space:pre"> </span><a href="http://ns2.google.com">ns2.google.com</a>.</div>
<div><a href="http://google.com">google.com</a>.<span class="" style="white-space:pre"> </span>96485<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>NS<span class="" style="white-space:pre"> </span><a href="http://ns3.google.com">ns3.google.com</a>.</div>
<div><a href="http://google.com">google.com</a>.<span class="" style="white-space:pre"> </span>96485<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>NS<span class="" style="white-space:pre"> </span><a href="http://ns4.google.com">ns4.google.com</a>.</div>
<div><a href="http://google.com">google.com</a>.<span class="" style="white-space:pre"> </span>96485<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>NS<span class="" style="white-space:pre"> </span><a href="http://ns1.google.com">ns1.google.com</a>.</div>
<div><br></div><div>;; ADDITIONAL SECTION:</div><div><a href="http://ns3.google.com">ns3.google.com</a>.<span class="" style="white-space:pre"> </span>108462<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>A<span class="" style="white-space:pre"> </span>216.239.36.10</div>
<div><a href="http://ns4.google.com">ns4.google.com</a>.<span class="" style="white-space:pre"> </span>108462<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>A<span class="" style="white-space:pre"> </span>216.239.38.10</div>
<div><a href="http://ns1.google.com">ns1.google.com</a>.<span class="" style="white-space:pre"> </span>108462<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>A<span class="" style="white-space:pre"> </span>216.239.32.10</div>
<div><a href="http://ns2.google.com">ns2.google.com</a>.<span class="" style="white-space:pre"> </span>108462<span class="" style="white-space:pre"> </span>IN<span class="" style="white-space:pre"> </span>A<span class="" style="white-space:pre"> </span>216.239.34.10</div>
<div><br></div><div>;; Query time: 22 msec</div><div>;; SERVER: 141.161.100.201#53(141.161.100.201)</div><div>;; WHEN: Sun Jul 06 12:42:09 EDT 2014</div><div>;; MSG SIZE rcvd: 207</div></div><div><br></div><div><br></div>
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