coredns: CoreDNS misbehaving for outside Kuberentes queries

CoreDNS fails to respond to queries relating to the outside Kuberntes cluster. I have enabled logging in my configuration.

10.244.1.155:40796 - [12/Nov/2018:08:39:03 +0000] 19104 "A IN acme-v02.api.letsencrypt.org.ingress.svc.cluster.local. udp 72 false 512" NXDOMAIN qr,rd,ra 165 0.000410577s
10.244.1.155:51013 - [12/Nov/2018:08:39:03 +0000] 29141 "AAAA IN acme-v02.api.letsencrypt.org.svc.cluster.local. udp 64 false 512" NXDOMAIN qr,rd,ra 157 0.000425219s
10.244.1.155:58880 - [12/Nov/2018:08:39:03 +0000] 35055 "A IN acme-v02.api.letsencrypt.org.svc.cluster.local. udp 64 false 512" NXDOMAIN qr,rd,ra 157 0.000842194s
10.244.1.155:53611 - [12/Nov/2018:08:39:03 +0000] 279 "AAAA IN acme-v02.api.letsencrypt.org.cluster.local. udp 60 false 512" NXDOMAIN qr,rd,ra 153 0.000158279s
10.244.1.155:57644 - [12/Nov/2018:08:39:03 +0000] 26214 "A IN acme-v02.api.letsencrypt.org.cluster.local. udp 60 false 512" NXDOMAIN qr,rd,ra 153 0.000582892s
10.244.1.155:53330 - [12/Nov/2018:08:39:03 +0000] 23888 "AAAA IN acme-v02.api.letsencrypt.org.local. udp 52 false 512" NXDOMAIN qr,rd,ra 52 0.001675627s
10.244.1.155:41214 - [12/Nov/2018:08:39:03 +0000] 49764 "A IN acme-v02.api.letsencrypt.org.local. udp 52 false 512" NXDOMAIN qr,rd,ra 52 0.002842832s
10.244.1.155:58355 - [12/Nov/2018:08:39:03 +0000] 589 "A IN acme-v02.api.letsencrypt.org. udp 46 false 512" SERVFAIL qr,rd 46 0.008358253s2018/11/12 08:39:03
[ERROR] 0 acme-v02.api.letsencrypt.org. A: unreachable backend: no upstream host