My host system is an Ubuntu 17.04 installation. I'm running a Windows virtual machine using VirtualBox. My network adapter is configured to use NAT. I was facing issues in which DNS resolving in the guest system was not equal to DNS resolving in the host system. To enforce this, I had the run the following configuration setting in the host system:
$ VBoxManage modifyvm "VM name" --natdnshostresolver1 on
--natdnshostresolver<1-N> on|off: This setting makes the NAT engine use the host's resolver mechanisms to handle DNS requests. Please see Section 9.11.5, “Enabling DNS proxy in NAT mode” for detailsx).