Comment 1 for bug 1795718

So i think the issue here might be that unbound is not properly caching the registry-1.docker.io dns lookup due to the config.

http://logs.openstack.org/25/602425/5/check/tripleo-ci-centos-7-containers-multinode/e2bb2ec/logs/undercloud/etc/unbound/conf.d/ttl.conf.txt.gz
# Ansible managed

server:
    cache-min-ttl: 900
    cache-max-ttl: 86400

Unfortunately the TTL for docker.io is 900 so it's skipping the cache.

Oct 02 16:52:43 unbound[1731:1] info: incoming scrubbed packet: ;; ->>HEADER<<- opcode: QUERY, rcode: NOERROR, id: 0
;; flags: qr rd ra ; QUERY: 1, ANSWER: 0, AUTHORITY: 1, ADDITIONAL: 0
;; QUESTION SECTION:
docker.io. IN DS

;; ANSWER SECTION:

;; AUTHORITY SECTION:
io. 900 IN SOA a0.nic.io. noc.afilias-nst.info. 1497465179 10800 3600 2764800 900

;; ADDITIONAL SECTION:
;; MSG SIZE rcvd: 90
http://logs.openstack.org/73/607173/1/gate/tripleo-ci-centos-7-containerized-undercloud-upgrades/703ce71/logs/undercloud/var/lib/unbound/unbound.log.txt.gz