[Openstack-operators] [neutron] Instances on private net can't resolve, no DNS

chrishull42 at gmail.com chrishull42 at gmail.com
Thu Mar 31 05:04:31 UTC 2016


Hi James.  

That makes sense.   I had tried that.  Doesn't seem to work.   I'd think the public and private subnets would behave the same way.  Public works but private doesn't.   Private can ping though 

Telnet can't get to port 53 from an instance on the private net. 

Public net can use my ATT router gateway as DNS too. 

Wondering if Neutron router is to blame... again.  :)

Thanks
Chris. 

Sent from my iPhone

> On Mar 30, 2016, at 9:20 PM, James Denton <james.denton at rackspace.com> wrote:
> 
> Hi Chris,
> 
> It shouldn't be as complex as that. DNS nameservers are pushed to instances via DHCP, and those name servers are set during subnet creation. You can also do a 'neutron subnet-update' to update an existing subnet.
> 
> Syntax:
> neutron subnet-update <subnet> --dns-nameservers <dns1> <dns2>
>> That would be used to update the subnet your instances attach to and not the external subnet attached to the router. Hope that helps.
> 
> James
> 
> 
>  
> From: Christopher Hull <chrishull42 at gmail.com>
> Sent: Wednesday, March 30, 2016 11:06 PM
> To: openstack-operators
> Subject: [Openstack-operators] [neutron] Instances on private net can't resolve, no DNS
>  
> Hello all;
>   
> Well, more pulling of teeth it seems before I actually get to USE my self-installed OpenStack Liberty.  :-)
> 
> All networks seem to work just fine.  Can ping everything from private network.  You would think DNS would work, but it doesn't    This I think has something to do with dnsmasq.   
> 
> I've read a few web pages.   Set dnsmasq_dns_servers in dhcp_agent.ini to 8.8.8.8,8.8.4.4 (Google DNS).   Also set the private subnet to those.   Nada.
> 
> From within an instance on the Private network, telnet 8.8.8.8 53 "no route to host".... but it PINGS!   Hmmm.  
> 
> So help me unravel more of this genome known as OpenStack.  Why if private instances can reach the internet, doens't DNS work????
> 
> Just patched Neutron to fix the previous bug.  I think I have the latest.
> 
> Thanks
> -Chris
> 
> 
> - Christopher T. Hull
> I am presently seeking a new career opportunity  Please see career page
> http://chrishull.com/career
> 333 Orchard Ave, Sunnyvale CA. 94085
> (415) 385 4865
> chrishull42 at gmail.com
> http://chrishull.com
> 
> 
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