What is the main functionality of a subnet mask?

The main functionality of a subnet mask is to separate and distinguish the network ID from the host ID within an IP address. A subnet mask is a 32-bit number that works in conjunction with an IP address to identify which part of the address refers to the network and which part refers to the specific device (host) within that network.

When a device wants to communicate over the internet or within a local network, it utilizes the IP address and the subnet mask together to determine if the destination device is on the same network or a different one. The subnet mask accomplishes this by applying a bitwise AND operation with the IP address, enabling the device to parse and recognize the network portion that identifies the overall network and the host portion that specifies an individual device connected to that network.

This capability is essential for routing IP packets correctly and ensuring that data reaches the correct destination, making the subnet mask a crucial element of IP networking. It is important to note that the other choices do not represent the primary functionality of a subnet mask; for example, encrypting the IP address pertains to security measures, limiting broadcast traffic involves network configuration and design, and assigning IP addresses dynamically relates to DHCP protocols, which is a different function entirely.