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We are running a Zimbra server on 16.04. today we changed the ip address and location of the server. Most issues have been resolved other than name resolution. The server is listening on 127.0.0.1 but unable to resolve. If we change resolv.conf to 8.8.8.8 we can resolve, However, resolve.conf will get overwritten of course. interfaces is set up correctly with dns-nameservers 8.8.8.8 - not really sure why it is listening on 127.0.0.1?

Trying to understand why resolv.conf is reverting to 127.0.0.1 when dns-nameservers is correctly set? Note, we are not running dnsmasq. Also this is a basic virtual machine install (I dont believe Network Manager is installed)

Appologies if this is a simple question!

  • Have you reload the network configuration ? (or just reboot the machine ?) – Eraseth Jun 11 '18 at 8:35
  • both, but more recently by restarting networking.service – skyman Jun 11 '18 at 8:51
  • Can you reach the DNS server you try to configure ? (ping) – Eraseth Jun 11 '18 at 8:58
  • so dns-nameservers is set to 8.8.8.8 - which I can ping yes. I was trying to work out if there was any local DNS server running - but it appears not. netstat shows 127.0.0.1:55 - is this normal? – skyman Jun 11 '18 at 9:46
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The solution was as follows:

Zimbra does run a DNS cache which must be configured to reference an appropriate DNS server.

to check current DNS

zmprov getServer `zmhostname` | grep DNSMasterIP

to remove old DNS

zmprov ms `zmhostname` -zimbraDNSMasterIP  192.168.1.45

to add new DNS

zmprov ms `zmhostname` +zimbraDNSMasterIP  8.8.8.8

Zimbra's dnscache listens on 127.0.0.1 - we had the intenal reference DNS set to an old internal dns server rather than an external one.

dnscache will override resolve.conf in Ubuntu resetting it to 127.0.0.1

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