ZyXEL Communications Prestige 2002 - Manual (Page 127)

P-2002 Series User’s Guide
Appendix C 127
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
6 -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 51 Subnet 1
IP/SUBNET MASK 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:
192.168.1.63
Highest Host ID: 192.168.1.62
Table 52 Subnet 2
IP/SUBNET MASK 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 53 Subnet 3
IP/SUBNET MASK 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:
192.168.1.128
Lowest Host ID: 192.168.1.129
Broadcast Address:
192.168.1.191
Highest Host ID: 192.168.1.190