Your network contains an Active Directory domain named contoso.com. The domain contains a server named Server1 that runs Windows Server 2012 R2 and has
the DHCP Server server role installed.
You need to create an IPv6 scope on Server1. The scope must use an address space that is reserved for private networks. The addresses must be routable.
Which IPV6 scope prefix should you use?
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.
The address block fc00::/7 is divided into two /8 groups:
The block fc00::/8 has not been defined yet.
The block fd00::/8 is defined for /48 prefixes, formed by setting the 40 least-significant bits of the prefix to a randomly generated bit string.
Prefixes in the fd00::/8 range have similar properties as those of the IPv4 private address ranges:
They are not allocated by an address registry and may be used in networks by anyone without outside involvement.
They are not guaranteed to be globally unique.
Reverse Domain Name System (DNS) entries (under ip6.arpa) for fd00::/8 ULAs cannot be delegated in the global DNS.
Reference: RFC 4193