To confirm Toni's comment, my testing yields the same result:
$ vboxmanage --version 5.0.20r106931
$ vagrant --version Vagrant 1.8.1
$ vagrant box list | grep xenial ubuntu/xenial64 (virtualbox, 20160531.0.0)
$ vagrant init ubuntu/xenial64 $ vagrant up
$ vagrant ssh -- sudo grep hosts /etc/nsswitch.conf sudo: unable to resolve host ubuntu-xenial hosts: files dns
To confirm Toni's comment, my testing yields the same result:
$ vboxmanage --version
5.0.20r106931
$ vagrant --version
Vagrant 1.8.1
$ vagrant box list | grep xenial
ubuntu/xenial64 (virtualbox, 20160531.0.0)
$ vagrant init ubuntu/xenial64
$ vagrant up
$ vagrant ssh -- sudo grep hosts /etc/nsswitch.conf
sudo: unable to resolve host ubuntu-xenial
hosts: files dns