Comment 8 for bug 1558934

It appears dns_name was added to neutron client version 4.1.0. Presuming Kevin is using 4.1.1, this shouldn't be an issue.

Having said that, from the above logs Kevin posted, it's the neutron server returning this error but not the neutron client. So, I would check if neutron bits are latest. In Devstack you could run "$git log" under /opt/stack/neutron to see if you have the latest commits.

I did a fresh install of devstack an hour ago and I tried spare amp and failover with Single topology (though I don't think this error in anyway particularly related to Active-standby topology) and I don't see any such errors.