Table 19 Subnet 1; Table 20 Subnet 2; Table 21 Subnet 3 - ZyXEL Communications ZyWall 35 User Manual

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 2
1's is the broadcast address on the subnet).

Table 19 Subnet 1

IP Address
IP Address (Binary)
Subnet Mask (Binary)
Subnet Address: 192.168.1.0
Broadcast Address:
192.168.1.63

Table 20 Subnet 2

IP Address
IP Address (Binary)
Subnet Mask (Binary)
Subnet Address: 192.168.1.64
Broadcast Address: 192.168.1.127

Table 21 Subnet 3

IP Address
IP Address (Binary)
Subnet Mask (Binary)
Subnet Address:
192.168.1.128
Broadcast Address:
192.168.1.191
Appendix C IP Subnetting
6
-2 or 62 hosts for each subnet (all 0's is the subnet itself, all
NETWORK NUMBER
192.168.1.
11000000.10101000.00000001.
11111111.11111111.11111111.
Lowest Host ID: 192.168.1.1
Highest Host ID: 192.168.1.62
NETWORK NUMBER
192.168.1.
11000000.10101000.00000001.
11111111.11111111.11111111.
Lowest Host ID: 192.168.1.65
Highest Host ID: 192.168.1.126
NETWORK NUMBER
192.168.1.
11000000.10101000.00000001.
11111111.11111111.11111111.
Lowest Host ID: 192.168.1.129
Highest Host ID: 192.168.1.190
ZyWALL 35 User's Guide
LAST OCTET BIT
VALUE
0
00000000
11000000
LAST OCTET BIT
VALUE
64
01000000
11000000
LAST OCTET BIT
VALUE
128
10000000
11000000
597