kubectl: Kubectl fails to resolve names except through DNS

Is this a request for help? (If yes, you should use our troubleshooting guide and community support channels, see http://kubernetes.io/docs/troubleshooting/.): Not exactly

What keywords did you search in Kubernetes issues before filing this one? (If you have found any duplicates, you should instead reply there.): kubectl “unable to connect to the server” “read udp”

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Is this a BUG REPORT or FEATURE REQUEST? (choose one): BUG REPORT

Kubernetes version (use kubectl version):

$ kubectl version
Client Version: version.Info{Major:"1", Minor:"7", GitVersion:"v1.7.3", GitCommit:"2c2fe6e8278a5db2d15a013987b53968c743f2a1", GitTreeState:"clean", BuildDate:"2017-08-03T15:13:53Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"darwin/amd64"}

Environment:

• Cloud provider or hardware configuration: unknown
• OS (e.g. from /etc/os-release): macOS 10.12.6
• Kernel (e.g. uname -a): n/a
• Install tools: Homebrew
• Others:

What happened:

$ time kubectl version
Client Version: version.Info{Major:"1", Minor:"7", GitVersion:"v1.7.3", GitCommit:"2c2fe6e8278a5db2d15a013987b53968c743f2a1", GitTreeState:"clean", BuildDate:"2017-08-03T15:13:53Z", GoVersion:"go1.8.3", Compiler:"gc", Platform:"darwin/amd64"}
Unable to connect to the server: dial tcp: lookup kub1.mycorp.local on 192.168.14.1:53: read udp 192.168.14.131:49181->192.168.14.1:53: i/o timeout
kubectl version  0.11s user 0.02s system 0% cpu 16.153 total
$ ping kub1
PING kub1.mycorp.local (10.10.9.161): 56 data bytes
64 bytes from 10.10.9.161: icmp_seq=0 ttl=61 time=387.593 ms
$ python -c "import socket; print(socket.gethostbyname('kub1'))"
10.10.9.161

It takes 15+ seconds to fail to connect to the cluster master and fails because it can’t figure out the name.

192.168.14.1 is the IP address of my local wifi router. It doesn’t (and shouldn’t) know anything about kub1. As you can see ping and gethostbyname both resolve the name through the Cisco VPN client installed and connected on the host.

What you expected to happen:

kubectl should connect to kub1 and kub1.mycorp.local like any other application on my system. It shouldn’t be making UDP calls to the nameserver directly but should use the IP stack on the host.

Additionally, the command probably shouldn’t be attempting to connect for a version command. Preferable would be for the command to return the version immediately… and for this issue only to appear if a cluster-relevant command were issued.

How to reproduce it (as minimally and precisely as possible): See above.

Anything else we need to know: