It is probably this: https://github.com/kubernetes/dns/issues/186
You’ll see this less with CoreDNS but it looks like we are having a similar problem but less often: https://github.com/coredns/coredns/issues/1365 John On Jan 8, 2018, at 3:57 AM, k1.hedayat...@gmail.com<mailto:k1.hedayat...@gmail.com> wrote: 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? -- You received this message because you are subscribed to the Google Groups "Kubernetes user discussion and Q&A" group. To unsubscribe from this group and stop receiving emails from it, send an email to kubernetes-users+unsubscr...@googlegroups.com. To post to this group, send email to kubernetes-users@googlegroups.com. Visit this group at https://groups.google.com/group/kubernetes-users. For more options, visit https://groups.google.com/d/optout. -- You received this message because you are subscribed to the Google Groups "Kubernetes user discussion and Q&A" group. To unsubscribe from this group and stop receiving emails from it, send an email to kubernetes-users+unsubscr...@googlegroups.com. To post to this group, send email to kubernetes-users@googlegroups.com. Visit this group at https://groups.google.com/group/kubernetes-users. For more options, visit https://groups.google.com/d/optout.
