The Purpose of a Network Mask

C

The correct answer is C. It is used to identify the network to which an IP address belongs.

A network mask, also known as a subnet mask, is a 32-bit number used to divide an IP address into a network address and a host address. The network address identifies the network to which the IP address belongs, while the host address identifies the specific device on that network.

The network mask is a series of 1's and 0's that correspond to the bits in an IP address. The 1's in the network mask indicate the network portion of the IP address, while the 0's indicate the host portion.

For example, consider the IP address 192.168.1.1 with a network mask of 255.255.255.0. The network mask indicates that the first three octets (192.168.1) are the network portion of the IP address, while the last octet (1) is the host portion. This means that any device on the network with an IP address that starts with 192.168.1 is part of the same network.

Knowing the network to which an IP address belongs is important for routing traffic on a network. Devices use the network mask to determine whether a destination IP address is on the same network as the device or whether the traffic needs to be routed to another network.

Option A is incorrect because the maximum hop count of a subnetwork is determined by the Time-to-Live (TTL) field in the IP header, not the network mask.

Option B is incorrect because the network mask does not indicate whether an IP address is private or public. Private IP addresses are reserved for use on private networks and are not routable on the public Internet.

Option D is incorrect because the total number of bits in an IP address is always 32, and this information is not provided by the network mask.