IPv6 Address Types for Subnet Communication

B.

A IPv6 Unique Local Address is an IPv6 address in the block FC00::/7

It is the approximate IPv6 counterpart of the IPv4 private address.

It is not routable on the global Internet.

Note: In the past, Site-local addresses (FEC0::/10) are equivalent to private IP addresses in IPv4 but now they are deprecated.

Link-local addresses only used for communications within the local subnet.

It is usually created dynamically using a link-local prefix of FE80::/10 and a 64-bit interface identifier (based on 48-bit MAC address).

The IPv6 address type that provides communication between subnets and cannot route on the Internet is the Unique Local Address (ULA), also known as Local IPv6 address or Site-Local Address.

Unique Local Addresses (ULA) are similar to private IP addresses in IPv4, and they are used to provide unique addressing within a local network, without requiring the use of globally unique addresses. They are defined in RFC 4193 and are intended for use in private networks or for interconnecting private networks that do not need to be reachable from the global Internet.

Unlike link-local addresses, which are only used for communication between devices on the same network segment, ULAs are routable within a single site or organization, but not across the Internet. This means that ULAs can be used to establish communication between subnets within a network, but they cannot be used for Internet connectivity.

The other IPv6 address types listed in the question are:

• Link-local addresses (A): used for communication between devices on the same network segment, and they cannot be routed beyond that segment.
• Multicast addresses (C): used to send a single packet to multiple devices at the same time.
• Global Unicast addresses (D): similar to public IP addresses in IPv4, and they are used to provide unique addresses that can be routed across the Internet.

Therefore, the correct answer is B: Unique Local Address (ULA).