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Instances can't ping servers by their domain name

asked 2015-09-22 12:51:10 -0500

weeix gravatar image

I followed OpenStack Installation Guide for Ubuntu 14.04( ( step-by-step from chapter 1 to 6 (using neutron with 3 nodes).

However, after I launched an instance (chapter 12), I'm unable to ping from that instance like the example in the 'To access your instance using a virtual console' section ( (

Verify the ext-net external network:

$ ping -c 4
PING ( 56(84) bytes of data.
64 bytes from icmp_req=1 ttl=53 time=17.4 ms
64 bytes from icmp_req=2 ttl=53 time=17.5 ms
64 bytes from icmp_req=3 ttl=53 time=17.7 ms
64 bytes from icmp_req=4 ttl=53 time=17.5 ms

--- ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 3003ms
rtt min/avg/max/mdev = 17.431/17.575/17.734/0.143 ms

Here is my result:

$ ping -c 4
ping: bad address ''

And I'm quite sure that I didn't miss a thing about configuring dns servers. Every hosts can ping normally.

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I think there is no DNS set in your /etc/resolv.conf for that instance.

herrsergio gravatar imageherrsergio ( 2015-09-22 13:50:15 -0500 )edit

@herrsergionameserver lies within the instance's /etc/resolv.conf (instance's IP =, instance's gateway =

weeix gravatar imageweeix ( 2015-09-22 21:10:16 -0500 )edit

1 answer

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answered 2015-09-23 07:03:03 -0500

updated 2015-09-25 04:22:22 -0500

Have a look on your neutron networking node at :

the /etc/neutron/dhcp_agent.ini file, section DEFAULT, entry dnsmasq_dns_servers

you should add the DNS for your network here


I have the following in my OpenStack installation script:

openstack-config --set /etc/neutron/dhcp_agent.ini DEFAULT dnsmasq_dns_servers $(awk '/^nameserver/ {print $2}' /etc/resolv.conf)

It takes the actual DNS server (which may have come through DHCP) and put that in the neutron dnsmasq configuration...


Always try ping to be sure it is really a name service problem and not a network connectivity problem.

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I changed the vaule to dnsmasq_dns_servers =,, then did a # service neutron-dhcp-agent restart. It works - I can ping now. Thank you very much!

weeix gravatar imageweeix ( 2015-09-23 21:18:50 -0500 )edit

I am having same issue in new instance. Can ping but not or any other domain names. When I run service neutron-dhcp-agent restart, I get error - "Failed to restart neutron-dhcp-agent.service: Unit neutron-dhcp-agent.service not found." Any inputs as to what I may be missing

maruti gravatar imagemaruti ( 2017-01-20 06:37:04 -0500 )edit

BTW, I am running devstack on Ubuntu 16.04 server. When I run neutron agent-list command, DHCP agent is listed and I can see its alive field to be smiley ( :-) ) which I believe means that this agent is alive but don't know why I get neutron-dhcp-agent.service not found!

maruti gravatar imagemaruti ( 2017-01-20 06:56:44 -0500 )edit

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Asked: 2015-09-22 12:51:10 -0500

Seen: 1,412 times

Last updated: Sep 25 '15