<div dir="ltr">"<span style="font-size:12.8000001907349px">Google unicast public DNS servers"</span><div><span style="font-size:12.8000001907349px"><br></span></div><div><span style="font-size:12.8000001907349px">s/unicast/anycast/, I keep forgetting that term.</span></div></div><div class="gmail_extra"><br><div class="gmail_quote">On 22 March 2015 at 22:28, Amos Shapira <span dir="ltr"><<a href="mailto:amos.shapira@gmail.com" target="_blank">amos.shapira@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr">1. Sounds like the ip's in your resolv.conf are wrong. Where does the server get them from? ip's 8.8.8.8 and 8.8.4.4 are the Google unicast public DNS servers. They are reliable but it's not optimal for a server to have to reach out to them on every query.<div><br></div><div>2. The ssh login is possibly slow because the ssh server is configured to try to reverse-resolve the incoming client ip address for logging. Look for "UseDNS" in your SERVER config (/etc/sshd_config). The default is usually "no" but perhaps in your case it's on.</div><div><br></div><div>3. Telnet is not a good indicator of reachability of DNS servers, DNS is UDP based and usually even the TCP port 53 is blocked because no one is supposed to have to access it. On the other hand, traceroute (yes, good old traceroute, as opposed to ping and tcptraceroute) uses UDP packets and you can tell it to use port 53 as destination so perhaps try that (again - pass "-n" flag to it to stop it from failing to reverse-resolve the ip address of each response).</div><div><br></div><div>Good luck.</div></div><div class="gmail_extra"><br><div class="gmail_quote"><div><div class="h5">On 22 March 2015 at 22:13, Gabor Szabo <span dir="ltr"><<a href="mailto:gabor@szabgab.com" target="_blank">gabor@szabgab.com</a>></span> wrote:<br></div></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div><div class="h5"><div dir="ltr">I tried that, and although I am not sure what should I look for in there it seems to be claiming<div><br></div><div>
<p><span>rt_sigsuspend([];; connection timed out; no servers could be reached</span></p><p><span><br></span></p><p><span>I tried to telnet </span>72.14.179.5 53 (one of the DNS servers) and that did not got a response.</p><p><br></p><p>Anyway, Linode support told me to add this to the resolve.conf</p><p><span style="color:rgb(51,51,51);font-family:arial,helvetica,sans-serif;font-size:13.3000001907349px;background-color:rgb(244,244,255)">nameserver 8.8.8.8</span></p><p><span style="color:rgb(51,51,51);font-family:arial,helvetica,sans-serif;font-size:13.3000001907349px;background-color:rgb(244,244,255)">nameserver 8.8.4.4</span></p><div class="gmail_extra"><br></div><div class="gmail_extra">and that seemed to do the trick.</div><span><font color="#888888"><div class="gmail_extra"><br></div><div class="gmail_extra">Gabor</div></font></span><div><div><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Mar 22, 2015 at 1:00 PM, guy keren <span dir="ltr"><<a href="mailto:guy.choo.keren@gmail.com" target="_blank">guy.choo.keren@gmail.com</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><br>
run this on the host:<br>
<br>
strace host <a href="http://www.google.com" target="_blank">www.google.com</a><br>
<br>
and scan the output.<br>
<br>
more efficient then guessing.<br>
<br>
--guy<span><br>
<br>
On 03/22/2015 12:50 PM, Gabor Szabo wrote:<br>
</span><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex"><span>
Hi,<br>
<br>
I run an Ubuntu based VPS on Linode.<br>
I few hours ago the machine stopped resolving hostnames.<br>
I think it was after an "aptitude safe-upgrade" and a reboot, but I am<br>
not sure. Maybe was like this earlier.<br>
<br>
It takes ages to ssh to it, once I got to the machine I can ping IP<br>
addresses from it, but I cannot ping anything with a hostname.<br>
<br>
this is what I have in resolv.conf<br>
<br>
# cat /etc/resolv.conf<br>
<br></span>
domain <a href="http://members.linode.com" target="_blank">members.linode.com</a> <<a href="http://members.linode.com" target="_blank">http://members.linode.com</a>><br>
<br>
search <a href="http://members.linode.com" target="_blank">members.linode.com</a> <<a href="http://members.linode.com" target="_blank">http://members.linode.com</a>><span><br>
<br>
nameserver 72.14.179.5<br>
<br>
nameserver 72.14.188.5<br>
<br>
options rotate<br>
<br>
<br>
I tried to replace the nameservers with others that are listed in<br>
another of my servers, but that did not make a change.<br>
<br>
How can I track down what has the server stopped resolving hostnames?<br>
<br>
Accessing the server via HTTP work as expected.<br>
<br>
Gabor<br>
<br><br></span></blockquote></blockquote></div>
</div></div></div></div></div>
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