Comment 1 for bug 1717733

i think recheck is needed for this bug, because in my environment its working fine.

Also check in your external network whether you are able to resolve the hostname.

In my devstack setup, /etc/neutron/dhcp_agent.ini:
dnsmasq_local_resolv = True

For more information:
https://ask.openstack.org/en/question/82095/instances-cant-ping-servers-by-their-domain-name/

My environment output:
http://paste.openstack.org/show/621587/