Comment 32 for bug 1561250

I am able to reproduce this as well.

Example:

-------------------------------------------------------------------
$ vagrant --version
Vagrant 1.8.3

$ vboxmanage --version
5.0.20r106931

$ vagrant init ubuntu/xenial64

$ vagrant box list | grep xenial
ubuntu/xenial64 (virtualbox, 20160610.0.0)

$ vagrant up

$ vagrant ssh

ubuntu@ubuntu-xenial:~$ sudo cat /etc/hosts
sudo: unable to resolve host ubuntu-xenial
127.0.0.1 localhost

# The following lines are desirable for IPv6 capable hosts
::1 ip6-localhost ip6-loopback
fe00::0 ip6-localnet
ff00::0 ip6-mcastprefix
ff02::1 ip6-allnodes
ff02::2 ip6-allrouters
ff02::3 ip6-allhosts
-------------------------------------------------------------------

In the above command line log you can see "sudo: unable to resolve host ubuntu-xenial".
The error makes it difficult to automatically configure the vm because commands return non zero exit status due to this error.