Final answer:
In the example IPv6 address, fec0:1319:7700:f631 is the network prefix and 446a:5511:cc40:25ab is the interface ID, although the exact delineation requires the prefix length. The subnet identifier falls within the network prefix and isn't clearly specified without further context.
Step-by-step explanation:
In the given IPv6 address fec0:1319:7700:f631:446a:5511:cc40:25ab, the prefix is typically the first part of the address that is used to identify the network, and the rest is used to identify the interface within the network. In this address, fec0:1319:7700:f631 is the prefix.
However, without the prefix length specified, we cannot determine the exact cutoff between the network prefix and the subnet. Often the prefix length is written as /64, which would mean the first four quartets are the network prefix. The subnet identifier is part of the network prefix and typically immediately follows the global routing prefix (not clearly definable in this case without additional context).
The interface ID, which uniquely identifies an interface on a network on a particular subnet, is the latter part of the address usually comprising the last 64 bits.
Thus in this example, 446a:5511:cc40:25ab would represent the interface ID, assuming a 64-bit prefix is used.