D-Link DES-3326 User Manual - Subnet Masking
DES-3326 Layer 3 Fast Ethernet Switch User’s Guide
72
Switch Management and Operating Concepts
the last octet is set to “1”s for the broadcast address and that for a
Class A networks, the last three octets are set to “1”s for the
broadcast address.
Subnet Masking
A subnet mask can be applied to an IP address to identify the
network and the node parts of the address. A bitwise logical AND
operation between the IP address and the subnet mask results in
the Network Address (sometimes called the “Network Number”).
For our example:
00001010.00101010.01001001.11010010 10.42.73.210
Class A IP address
11111111.00000000.00000000.00000000 255.0.0.0
Class A Subnet Mask
00001010.00000000.00000000.00000000 10.0.0.0
Network
Address
The Default subnet masks are:
•
Class A – 11111111.00000000.00000000.00000000
255.0.0.0
•
Class B – 11111111.11111111.00000000.00000000
255.255.0.0
•
Class C – 1111111.11111111.11111111.00000000
255.255.255.0
Additional bits can be added to the default subnet mask for a given
Class to further subnet a network. This has the effect of making
the subnet mask ‘longer’. When a bitwise logical AND operation is
performed between the subnet mask and the IP address, the result
defines the network. Some restrictions apply to the network