What is indicated by a subnet mask?

A subnet mask is a key component in networking that defines the size of a subnet, which directly correlates to the number of devices that can be supported on a particular network. The subnet mask works hand in hand with an IP address to determine which portion of the address designates the network and which part can be used for host addresses.

For instance, a typical subnet mask of 255.255.255.0 allows for 256 total addresses, but only 254 of these can be assigned to devices, as one address is reserved for the network itself and one for the broadcast address. This means the subnet mask essentially delineates how many addresses are available for use in the network, thereby indicating the number of devices that can exist within that network segment.

The other options do not relate specifically to what the subnet mask indicates. Bandwidth, data type, and connection speed are governed by different factors and characteristics that do not pertain to how a subnet mask operates within a network. Thus, the choice regarding the number of devices allowed on a network is the most fitting in relation to the function of a subnet mask.