Hello,
I've set up a cluster in Azure using Kubespray, VMs are Ubuntu 16.04, and
Kubespray configs are pretty much default, after installation when I try to
resolve DNS name I get NXDOMAIN randomly.
I've tried instructions in this link:
https://kubernetes.io/docs/tasks/administer-cluster/dns-custom-nameservers/#debugging-dns-resolution
This is the response:
k1@azurekube1:~$ kubectl exec -it busybox -- nslookup kubernetes.default
Server: 10.233.0.3
Address 1: 10.233.0.3
Name: kubernetes.default
Address 1: 10.233.0.1 kubernetes.default.svc.azurekube.pinsvc.net
k1@azurekube1:~$ kubectl exec -it busybox -- time nslookup kubernetes.default
Server: 10.233.0.3
Address 1: 10.233.0.3 kube-dns.kube-system.svc.azurekube.pinsvc.net
nslookup: can't resolve 'kubernetes.default'
command terminated with exit code 1
real 0m 40.03s
user 0m 0.00s
sys 0m 0.00s
First query gets resolved but second does not. What's interesting is when I
don't get response it takes like 20, 30 or 40 seconds to respond. And I've
tried to increase logging in kube-dns, I don't see any warning or errors in
kubedns container, but dnsmasq has something like this:
I0108 11:48:16.711820 dnsmasq[14]: query[A]
kubernetes.default.svc.azurekube.pinsvc.net from 127.0.0.1
I0108 11:48:16.711913 dnsmasq[14]: cached
kubernetes.default.svc.azurekube.pinsvc.net is 10.233.0.1
I0108 11:48:19.686014 dnsmasq[14]: reply 10.233.0.3 is
kube-dns.kube-system.svc.azurekube.pinsvc.net
I0108 11:48:21.712354 dnsmasq[14]: query[A]
kubernetes.default.svc.azurekube.pinsvc.net from 127.0.0.1
I0108 11:48:21.712437 dnsmasq[14]: cached
kubernetes.default.svc.azurekube.pinsvc.net is 10.233.0.1
I0108 11:48:24.691391 dnsmasq[14]: query[AAAA] kubernetes.default from
10.233.124.134
I0108 11:48:24.691457 dnsmasq[14]: cached kubernetes.default is NXDOMAIN
I0108 11:48:25.462845 processUpdate {Version: Data:map[]}
I0108 11:48:25.462895 Config was unchanged (version )
I0108 11:48:26.712929 dnsmasq[14]: query[A]
kubernetes.default.svc.azurekube.pinsvc.net from 127.0.0.1
I0108 11:48:26.712986 dnsmasq[14]: cached
kubernetes.default.svc.azurekube.pinsvc.net is 10.233.0.1
I0108 11:48:29.691979 dnsmasq[14]: query[AAAA] kubernetes.default from
10.233.124.134
I0108 11:48:29.692043 dnsmasq[14]: cached kubernetes.default is NXDOMAIN
I0108 11:48:29.692204 dnsmasq[14]: query[AAAA]
kubernetes.default.default.svc.azurekube.pinsvc.net from 10.233.124.134
I0108 11:48:29.692532 dnsmasq[14]: forwarded
kubernetes.default.default.svc.azurekube.pinsvc.net to 127.0.0.1
I0108 11:48:29.692832 dnsmasq[14]: reply
kubernetes.default.default.svc.azurekube.pinsvc.net is NXDOMAIN
I0108 11:48:29.692999 dnsmasq[14]: query[AAAA]
kubernetes.default.svc.azurekube.pinsvc.net from 10.233.124.134
I0108 11:48:29.693076 dnsmasq[14]: cached
kubernetes.default.svc.azurekube.pinsvc.net is NODATA-IPv6
I0108 11:48:31.713324 dnsmasq[14]: query[A]
kubernetes.default.svc.azurekube.pinsvc.net from 127.0.0.1
I0108 11:48:31.713365 dnsmasq[14]: cached
kubernetes.default.svc.azurekube.pinsvc.net is 10.233.0.1
I've tried setting up cluster multiple times with Kubernetes 1.9 and 1.8.
I'm out leads to debug this situation. Why this happens randomly?
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