Which aspect of a subnet mask determines network capacity?

The differentiation between the network and host portions of an IP address, defined by the subnet mask, is pivotal in determining network capacity. The subnet mask identifies which bits in the IP address are used for the network portion (which indicates the specific network) and which bits are allocated for the host portion (which identifies individual devices within that network).

The greater the number of bits assigned to the network portion, the fewer bits are left for the host portion. Consequently, this affects how many unique hosts can be accommodated within that network. For instance, a subnet mask of 255.255.255.0 allows for 256 IP addresses (0-255), with one reserved for the network and one for the broadcast address, leaving 254 usable addresses.

Assessing network capacity fundamentally involves understanding how the subnet mask divides the available bits between network identification and device identification. Other options, while they reflect relevant aspects of networking, do not directly address how the aspect of the subnet mask affects the number of hosts and overall network capacity.