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<div class="moz-cite-prefix">Noticed after sending the original
email, the version I am using is 2.57. Could an upgrade fix this
issue?<br>
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<br>
<i><b>Regards,<br>
Stuart<br>
<br>
</b></i> </div>
On 02/15/2013 01:32 AM, Stuart Wilson wrote:<br>
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Hi,<br>
<br>
I have noticed lately on several machines using the local cable
ISP in my neck of the woods, that using the DHCP supplied DNS
servers from my ISP is significantly slower than using a global
DNS service like OpenDNS. With that in mind I configured the Linux
box I use at home to use OpenDNS. It was working great, until I
decided to fix it by adding DNSMASQ as a local caching server to
lighten the load. It works fine most of the time, but sometimes I
get intermittent failures to resolve names. At first I just
noticed delays getting to some websites, and occasionally it would
fail entirely. At times though it became unacceptable and failed a
lot. So, I started testing name resolution in a shell using the
"host" command, and found that it did indeed sometimes give me a
";; connection timed out; no servers could be reached" error. When
I specifically ask the host command to query the OpenDNS server
directly, bypassing DNSMASQ, it never fails and is always very
fast.<br>
<br>
I got really curious about this and captured some packets with
Wireshark. First of a host query going through DNSMASQ that
failed, and then one going directly to the DNS server. I did
indeed get no reply back on the query that failed. The only
difference I could find between the packets being sent to OpenDNS
by DNSMASQ, and those going direclty from the OS to OpenDNS, is
that the queries that failed from DNSMASQ had the DF (don't
fragment) bit set. Now it is quite possible I'm missing something
here, but it occurs to me that my using DNS servers half way
across the internet, rather than right down the street at the
local ISP, could be causing packets with the DF bit set to get
dropped. Is there any way to tell DNSMASQ to not set the DF bit?
Can anyone think of another reason why this is failing for me?<br>
<div class="moz-signature">-- <br>
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<br>
<i><b>Regards,<br>
Stuart<br>
<br>
<br>
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