Enable networking in VirtualBox Centos Client

The CentOS 7 iso does not enable networking during the installation, unlike Ubuntu. So your shiny new CentOS cannot get to the outside world.

Based on Stack Overflow - CentOS 7 VirtualBox no internet access.

Add the following to /etc/sysconfig/network-scripts/ifcfg-enp0s3

DNS1=8.8.8.8
DNS2=8.8.4.4
# Note this was set to no
ONBOOT=yes