Final answer:
Netmask determines how many leading bits in the IP address contribute to its network address.
Step-by-step explanation:
Netmask determines how many leading bits in the IP address contribute to its network address. A netmask is a 32-bit number that is used to divide an IP address into network and host portions. The netmask contains a series of 1s followed by a series of 0s. The 1s in the netmask determine the network portion of the IP address.