ZyXEL p-334wh Guia Do Utilizador

P-334WH User’s Guide

Appendix D IP Addresses and Subnetting

231

Host IDs of all zeros represent the subnet itself and host IDs of all ones are the broadcast 
address for that subnet, so the actual number of hosts available on each subnet in the example 
above is 2

7

 – 2 or 126 hosts for each subnet.

192.168.1.0 with mask 255.255.255.128 is the subnet itself, and 192.168.1.127 with mask 
255.255.255.128 is the directed broadcast address for the first subnet. Therefore, the lowest IP 
address that can be assigned to an actual host for the first subnet is 192.168.1.1 and the highest 
is 192.168.1.126. Similarly the host ID range for the second subnet is 192.168.1.129 to 
192.168.1.254.

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 (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 2

6

-2 or 62 hosts for each subnet (all zeroes is the subnet itself, 

all ones is the broadcast address on the subnet). 

Subnet Address: 192.168.1.0

Lowest Host ID: 192.168.1.1

Broadcast Address: 

192.168.1.127

Highest Host ID: 192.168.1.126

Table 95   Subnet 2 

IP Address

192.168.1.

128

IP Address (Binary)

11000000.10101000.00000001. 

10000000

Subnet Mask

255.255.255.

128

Subnet Mask (Binary)

11111111.11111111.11111111. 

10000000

Subnet Address: 

192.168.1.128

Lowest Host ID: 192.168.1.129

Broadcast Address: 

192.168.1.255

Highest Host ID: 192.168.1.254

Table 94   Subnet 1 (continued)

Table 96   Subnet 1 

IP Address

192.168.1.

0

IP Address (Binary)

11000000.10101000.00000001. 

00000000

Subnet Mask (Binary)

11111111.11111111.11111111. 

11000000