A mask used to determine what subnet an IP address belongs to. An IP address has two components, the network address and the host address. For example, consider the IP address 150.215.017.009. Assuming this is part of a Class B network, the first two numbers (150.215) represent the Class B network address, and the second two numbers (017.009) identify a particular host on this network. Subnetting Subnetting enables the network administrator to further divide the host part of the address into two or more subnets. In this case, a part of the host address is reserved to identify the particular subnet. This is easier to see if we show the IP address in binary format.

1. Presented by
Ravi Namboori

2.  Introduction
 Fundamentals
 Subnet Network ID
 Finding Subnet Address
 Benefits

3. Subnetting is the foundation underlying the
expansion of both Local Networks & the Internet in
today’s world.Subnetting has become essential
knowledge for the Administrator of any network.

4. There are 2 fundamental reasons why subnetting has so much importance in
today’s networking environment:
The world is running out of available IP addresses. There just isn’t an
unlimited number of IP addresses available & subnetting helps extend the
existing addresses until either the next version of IP is rolled out or some
other technology charges on the scene.
Subnetting reduces the size of the routing tables stored in routers.
Subnetting extends the existing IP address base & restructures the IP
address. As a result, routers must have a way to extract from a IP address
both the Network address & the Host address.

5. A 3-step example of how the default Class A subnet mask is
applied to a Class A address:

6. 138. 101. 114. 250
IP Address 10001010 01100101 01110010 11111010
Mask 11111111 11111111 11111111 11000000
Network 10001010 01100101 01110010 11000000
138 101 114 192
Determine the Network (or Subnet) where this Host address lives:
1. Draw a line under the mask
2. Perform a bit-wise AND operation on the IP Address and the Subnet Mask
Note: 1 AND 1 results in a 1, 0 AND anything results in a 0
3. Express the result in Dotted Decimal Notation
4. The result is the Subnet Address of this Subnet or “Wire” which is
138.101.114.192

7. The 2 primary benefits of subnetting are:
1. Fewer IP addresses, often as few as one, are needed to
provide addressing to a network & subnetting.
2. Subnetting usually results in smaller routing tables in
routers beyond the local internetwork.

8. Thank You