Explanation/Reference:
Explanation:
Virtual switches/ Hyper-V VLAN - you can create 3 different types of virtual switches depending the needs of your virtual machines and one single machine can use multiple virtual NICs that is member of different Virtual Switches.
External - This virtual switch binds to the physical network adapter and create a new adapter you can

see in Control Panel\Network and Internet\Network Connections so if a virtual machine needs contact outside the host machine this one is a must.
Internal - This virtual switch can be used to connect all virtual machines and the host machine but

cannot go outside that.
Private - This virtual switch can only be used by the virtual host


Configuring Virtual Networks Private will not allow communication with the host machine. External will allow communication with the host machine but also allow access to other machines on the host machine's network which is not a requirement.
References:
http://john.bryntze.net/jbkb-v2/certification-exam-70-687-configuring-windows-8-part-2-configure-hardware- and-applications-16/