What is the representation of the IPv6 unspecified address?

The IPv6 unspecified address is represented as "::". This notation translates to an address where all 128 bits are set to zero, indicating that the device does not have a specific address assigned to it at that time.

This address is typically used in scenarios where a node wishes to indicate that it does not have an address or in applications where an address is yet to be assigned. For instance, during the process of configuration or before obtaining a valid address, a device might use the unspecified address to identify itself.

The representation "::" is a shorthand notation in IPv6 that condenses contiguous sections of zeros into a singular double colon, making it easier to read and write.

In contrast, "::1" represents the loopback address, which is used by a device to send packets to itself. The address "0::" could be interpreted as an unspecified address, but this format is not standard. The address "FFFF::" represents a broadcast address that is used in certain IPv6 multicast situations, which is not related to the unspecified address.

Thus, "::" is the correct representation of the IPv6 unspecified address.