What is Subnet Mask? Definition & FAQs | Network Life

SUBNET MASK // 

 

A subnet mask is a 32- or 128-bit number that segments an existing IP address in a TCP/IP network. It is used by the TCP/IP protocol to determine whether a host is on the local subnet or on a remote network. Subnet mask divides the IP address into a network address and host address, hence to identify which part of the IP address is reserved for the network and which part is available for host use.

 

 

A subnet mask is a group of four numbers that define what IP network the computer

is a member of. All of the 255s in a subnet mask collectively refer to the network portion,

while the 0s refer to the host portion. This is illustrated in Table 1.1. This table shows

a typical Class C IP address and the default corresponding subnet mask. If you were to

configure the IP address of a Windows computer as 192.168.1.1, Windows would automatically

default to a subnet mask of 255.255.255.0. If any other computers would like

to communicate with yours, they need to be configured with the same network number;

however, every computer on the same network needs to have a different host number or an

IP conflict might ensue. Of course, as a talented administrator, you’ll learn how to avoid IP

conflicts