Binary

Binary is a basic building block in networking. We use binary for IP addressing, sub-netting, access lists, inverse masks etc.

As someone said "There are 10 kinds of people in the world, those who understand binary and those that don't" All computers function by using a system of switches that can either be 'on' or 'off' being denoted by off=0 or on=1

Binary vs Decimal

An analogy is 2 electrical cables. The cables can either have electricity run through them (ie "on" therefore = 1) of no current on them (ie "off = 0) As seen each cable has 2 states, either on or off.Therefore 2 cables with 2 states, the total amount of states is 2 x 2 =4 or $2^2$ 00, 01, 10, 11 = off-off, of-on, on-off and on-on

Now, extending the above from 2 cables to 8 (this is because an IP address has 4 octets ( or four, eight bit values) 12345678.12345678.12345678.12345678

Looking at the first octet (8 bit value) the number of states that these 8 "cables" can be it would be 2x2x2x2x2x2x2x2 or $2^8 = 256$binary combinations

Lets do some maths $2^0 = 1$ $2^1=2$ $2^2 = 4$ $2^3=8$ $2^4=16$ $2^5=32$ $2^6=64$ $2^7=128$ $2^8=256$

Decimal is a 10 Base System - 0 to 9 Binary is a 2 Base System - 0 to 1

A Famous Table:

If all 8 Cables was set to "ON" then the value would be 255

An example from the above would be "What is the binary of the following decimal values:

DECIMAL	BINARY
1	00000001
192	11000000
253	11111101

IP Address Example

	OCTET 1	OCTET 2	OCTET3	OCTET4
DECIMAL	172	16	60	5
BINARY	101101100	00001000	00111100	00000101