ZyXEL p-334wh Guia Do Utilizador

P-334WH User’s Guide

230 

Appendix D IP Addresses and Subnetting

The first mask shown is the class “C” natural mask. Normally if no mask is specified it is 
understood that the natural mask is being used.

As an example, you have a class “C” address 192.168.1.0 with subnet mask of 255.255.255.0. 

Table 93   Two Subnets Example 

IP Address

192.168.1.

0

IP Address (Binary)

11000000.10101000.00000001.

00000000

Subnet Mask

255.255.255.

0

Subnet Mask (Binary)

11111111.11111111.11111111.

00000000

The first three octets of the address make up the network number (class “C”). 

To make two networks, divide the network 192.168.1.0 into two separate subnets by 
converting one of the host ID bits of the IP address to a network number bit. The “borrowed” 
host ID bit can be either “0” or “1” thus giving two subnets; 192.168.1.0 with mask 
255.255.255.128 and 192.168.1.128 with mask 255.255.255.128.

Note: In the following charts, shaded/bolded last octet bit values indicate host ID bits 

“borrowed” to make network ID bits. The number of “borrowed” host ID bits 
determines the number of subnets you can have. The remaining number of 
host ID bits  (after “borrowing”) determines the number of hosts you can have 
on each subnet.

255.255.255.240

/28

1111 0000

240

255.255.255.248

/29

1111 1000

248

255.255.255.252

/30

1111 1100

252

Table 92   Alternative Subnet Mask Notation (continued)

Table 94   Subnet 1 

IP Address

192.168.1.

0

IP Address (Binary)

11000000.10101000.00000001. 

00000000

Subnet Mask

255.255.255.

128

Subnet Mask (Binary)

11111111.11111111.11111111. 

10000000