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I have a fresh install of Ubuntu 14.04 running inside a docker container.

I have a working network connection:

PING 93.184.216.34 (93.184.216.34) 56(84) bytes of data.
64 bytes from 93.184.216.34: icmp_seq=1 ttl=53 time=71.3 ms

However I seem to be unable to resolve domain names:

ping: unknown host www.example.com

It should be using OpenDNS

>> cat /etc/resolv.conf 
nameserver 208.67.222.222
nameserver 208.67.220.220

The OpenDNS IP addresses respond to ping

PING 208.67.222.222 (208.67.222.222) 56(84) bytes of data.
64 bytes from 208.67.222.222: icmp_seq=1 ttl=53 time=3.57 ms

But domain name resolution still isn't working.

What might be causing this, and how could I diagnose and fix the problem?

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  • Can you post the output of nslookup google.com 208.67.222.222? Oct 26, 2015 at 14:51
  • ;; connection timed out; no servers could be reached
    – TDN169
    Oct 26, 2015 at 14:55
  • Can you try using Google's public DNS at 8.8.8.8 or 8.8.4.4? Oct 26, 2015 at 14:56
  • Google DNS doesn't work, however our own corporate DNS works - any ideas why that might be?
    – TDN169
    Oct 26, 2015 at 15:01

1 Answer 1

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If neither OpenDNS or Google's DNS public DNS servers respond, you most likely have firewall rules preventing your server from making outbound requests on port 53.

I would check your local firewall rules, or your network's negress rules.

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  • I'm using our own DNS now without any problems, so I think that must be it.
    – TDN169
    Oct 26, 2015 at 15:07

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