Docker login: Dial tcp: lookup index.docker.io read udp i/o timeout

[gavinmroy]

I believe I’ve tracked this down to truncated DNS responses from upstream DNS causing Docker’s embedded DNS server to fail since it seem to be listening via TCP:

Auth.docker.io on 192.168.65.1:53: no such host

So I’ve done a bit of research on this today (that is most of my day has been taken up in researching this). My findings thus far: This has something to do with the EDNS record sizes returned for auth.docker.io and the new Alpine 3.4 based moby image. Previous versions of moby on my network do not have the issue The error that I get is a failure to connect to the embedded DNS server in docker via TCP On my network, I am getting EDNS truncated responses back which should cause the DNS resolver…