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Every few minutes, when I request a web page, I get a DNS lookup failure. Usually, if I just immediately refresh, the web page will come up. However, recently the DNS failures have been persisting for long periods of time, even across restarts (though eventually, it always starts working again, at least for a while). It happens in Chrome, Firefox, Thunderbird, and Update Manager. When this happens, if I ping a host name like, I get an unknown host message, but if I ping an IP address, it works fine.

I'm also running Windows 7 in a VMWare virtual machine on the Ubuntu host, and if I switch to the VM, I have no problems, even when the host Ubuntu is having DNS failures.

Note, I'm using a wired ethernet connection.

Thanks for any help.

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up vote 4 down vote accepted

Try this. Just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:

sudo gedit /etc/NetworkManager/NetworkManager.conf

Comment out the line that says dns=dnsmasq

enter image description here

Once done, restart network Manager

sudo restart network-manager
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Thank you. I'll give this a try and report back if it works. Are there any negative consequences to commenting out the dns=dnsmasq line? Why does that cause these intermittent failures? Has a bug been filed about this? – Anthony Jun 5 '13 at 18:55
No negative consequences. Once you try it, will go from there. – Mitch Jun 5 '13 at 19:07
Well, no further problems so far, so I'm cautiously optimistic that this is the solution. Still, it seems like this should be considered a bug, no? – Anthony Jun 5 '13 at 22:10

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