Comment 19 for bug 1584042

This issue could exist since a long time. Having only 3 servers, each nameserver, did hide the problem (as each could resolve)
In my numerous tests, I made a virtual machine using an old Ubuntu server 15.04 and the problem was present. But,in the meanwhile, my bind server was having troubles (rx/tx activated). So I don't know if its due to 15.04 or the production bind server

I'll try to test on the upstream build as soon as possible. I'll tell you