HP-UX LAN Administrator's Guide (Feburary 2007)

Network AddressingDRAFT COPY
Subnet Addresses
Chapter 7106
Figure 7-4 shows how a Class C Internet address and a subnet mask combine to form a subnet
address.
Figure 7-4 Internet Address 192.6.12.33 ANDed with Subnet Mask
255.255.255.224
When the internet address is ANDed with the subnet mask, the zero values in the host
portion of the subnet mask will “overwrite” the corresponding bits of the host portion of the
internet address and the resultant subnet address will be 192.6.12.32 as shown in Figure 7-4
above. Non-zero values in the subnet mask indicate that the corresponding bits in the
internet address do not change. The subnet mask may be fixed-length or variable-length.
IP Subnet Mask
11 1111111111 11111111110011111 000
11 0000001100 00011000010000000 001
11 0000001100 00011000010000000 000
255 . 255 . 255 . 224
Subnet
Mask
AND
0 values in mask (00000)
192 . 6 . 12 . 33
Internet
Address
Convert
to
Subnet
Address
overwrite value of 1 (00001)
in IP address
Bit values unchanged
Bit values
converted to
zero
resulting in new value
(00100000) in host address
(or 32 in dot notation)
192 . 6 . 12 . 32