Explanation:
* The localhost (loopback) address, 0:0:0:0:0:0:0:1, and the IPv6 unspecified address,
0:0:0:0:0:0:0:0, are reduced to ::1 and ::, respectively.
* A unique local address (ULA) is an IPv6 address in the block fc00::/7, defined in RFC 4193. It is the approximate IPv6 counterpart of the IPv4 private address.
* Link-local addresses for IPv4 are defined in the address block 169.254.0.0/16, in CIDR notation.
In IPv6, they are assigned with the fe80::/10 prefix.

Explanation/Reference:
The full range of multicast addresses is from 224.0.0.0 to 239.255.255.255.

Explanation/Reference:
VPN is a network that is constructed by using public wires - usually the Internet - to connect to a private network, such as a company's internal network.
There are a number of systems that enable you to create networks using the Internet as the medium for transporting data. These systems use encryption and other security mechanisms to ensure that only authorized users can access the network and that the data cannot be intercepted.