ZyXEL Communications G-1000 manual Example Four Subnets

G-1000 User’s Guide

Example: Four Subnets

The above example illustrated using a 25-bit subnet mask to divide a class “C” address space into two subnets. Similarly to divide a class “C” address into four subnets, you need to “borrow” two host ID bits to give four possible combinations of 00, 01, 10 and 11. The subnet mask is 26 bits (11111111.11111111.11111111.11000000) or 255.255.255.192. Each subnet contains 6 host ID bits, giving 26-2 or 62 hosts for each subnet (all 0’s is the subnet itself, all 1’s is the broadcast address on the subnet).

Table 77 Subnet 1

	NETWORK NUMBER	LAST OCTET BIT
		VALUE
IP Address	192.168.1.	0
IP Address (Binary)	11000000.10101000.00000001.	00000000
Subnet Mask (Binary)	11111111.11111111.11111111.	11000000
Subnet Address: 192.168.1.0	Lowest Host ID: 192.168.1.1
Broadcast Address:	Highest Host ID: 192.168.1.62
192.168.1.63

Table 78 Subnet 2

	NETWORK NUMBER	LAST OCTET BIT
		VALUE
IP Address	192.168.1.	64
IP Address (Binary)	11000000.10101000.00000001.	01000000
Subnet Mask (Binary)	11111111.11111111.11111111.	11000000
Subnet Address: 192.168.1.64	Lowest Host ID: 192.168.1.65
Broadcast Address: 192.168.1.127	Highest Host ID: 192.168.1.126

Table 79 Subnet 3

	NETWORK NUMBER	LAST OCTET BIT
		VALUE
IP Address	192.168.1.	128
IP Address (Binary)	11000000.10101000.00000001.	10000000
Subnet Mask (Binary)	11111111.11111111.11111111.	11000000
Subnet Address:	Lowest Host ID: 192.168.1.129
192.168.1.128
Broadcast Address:	Highest Host ID: 192.168.1.190
192.168.1.191

174 IP Subnetting