1.10-rc1 embedded DNS obscures third party domains

[awh]

vagrant@vagrant-ubuntu-vivid-64:~$ docker version
Client:
 Version:      1.10.0-rc1
 API version:  1.22
 Go version:   go1.5.3
 Git commit:   677c593
 Built:        Fri Jan 15 18:17:17 2016
 OS/Arch:      linux/amd64

Server:
 Version:      1.10.0-rc1
 API version:  1.22
 Go version:   go1.5.3
 Git commit:   677c593
 Built:        Fri Jan 15 18:17:17 2016
 OS/Arch:      linux/amd64

Resolution of <name> and <name>.<network>:

vagrant@vagrant-ubuntu-vivid-64:~$ docker network create mynet
89676bd57d2dcd9169633c309f9fba0e272d105b5738834e8d06654de675f513
vagrant@vagrant-ubuntu-vivid-64:~$ docker run --net mynet --name foo -ti ubuntu
root@7e1e0773fdac:/# getent hosts foo
172.21.0.2      foo
root@7e1e0773fdac:/# getent hosts foo.mynet
172.21.0.2      foo.mynet

Which I believe is the intended behaviour. This is probably unintended however:

root@7e1e0773fdac:/# getent hosts foo.mynet.google.com
172.21.0.2      foo.mynet.google.com

This request should have been delegated to external DNS.

[vdemeester]

/cc @mavenugo

Also see these two comments : #19403 (comment)

[sanimej]

@awh Yes, resolution for foo.mynet.google.com should be delegated to external DNS. Will fix it in the next RC image. Thanks.

[sanimej]

@vdemeester This is different from what is being asked in #19403

[thaJeztah]

Looks like this should be resolved by #19573, so closing.

Thanks for testing our RC's and reporting this issue @awh! ❤️