1. Classic Classful addresses
A 1-126 , B 128 – 191, C 192 – 223
A /8, B /16, C /24
Subnetting
Making a smaller network from the classic classes to avoid wasting an entire class C network for
networks with fewer users
Variable Length Subnet Mask (VLSM)
Dividing a network into different sized subnets. It is like making a subnet from a subnet. Starting
with the largest it creates
IPv4 Addresses
32-bit address divided into four blocks of eight binary numbers called octets.
Binary Numbers
Base 2 numbering system. Computers use this system because it can be represented easily by
electrical circuits. Convert binary to decimal by adding up the turned on numbers. 0-255
possible values
128 64 32 16 8 4 2 1
Covert a decimal number to binary by checking the number against the greatest values, turn on
that value, subtract, and repeat through.
Subnet Mask
Also a 32-bit binary number. It is used to divide the network portion of the IP from the host
portion
11111111.11111111.11111111.00000000 is what the computer sees for 255.255.255.0 or /24
11111111. 11111111. 11111111.11100000
*Anding*
Calculations
2net = Number of subnets
2host – 2 = Number of usable IP address
*Magic number*
