23. Binary Addressing

Computers use binary numbers for all computations. Most computers are set up in 8 bit scheme. A bit is 1 character, either a one (1) or a zero (0). All characters are translated into in a series of 8 one’s or zero’s. The letter A for example would be represented by 01100011 (not actual) to the computer. A 1(one) represents power on, while a 0 (zero) represents power off. This is how computers communicate. Here is how the binary addressing system works:

Binary Value
128 64 32 16 8 4 2 1

So below we will take a sample number and decipher it below: (the number is 143)
1 0 0 0 1 1 1 1

How could we tell that 10001111 was the same as 143 in binary? Well using the binary value table of 128,64,32,16,8,4,2 and 1, we added the numbers that had a 1 in that value holder. There was a 1 in the 128 value, and a 1 in the 8,4,2 and 1 value holders. We add these numbers together to get our answer (128+8+4+2+1=143). When there is a one in all the value holders then the number is 255 (128+64+32+16+8+4+2+1=255), so 255 is the highest number in an 8 bit addressing scheme.

Subnet bits are more complicated. They are taken from the consecutive high order bits, as seen in the following table:

Subnet Bits
Value 128 64 32 16 8 4 2 1
1 bit 1 0 0 0 0 0 0 0
2 bit 1 1 0 0 0 0 0 0
3 bit 1 1 1 0 0 0 0 0
4 bit 1 1 1 1 0 0 0 0
5 bit 1 1 1 1 1 0 0 0
6 bit 1 1 1 1 1 1 0 0
7 bit 1 1 1 1 1 1 1 0
8 bit 1 1 1 1 1 1 1 1

Using the preceding information, we can now see that for the sample IP address of 192.168.0.1 (this is the address reserved for private networks not connected to the Internet) we can find the following information:

Note: on the network and host part, don’t forget we are dealing with a Class C address, so the first three sets of numbers are the network, while the last number is the host (or specific machine if not subnetted.)

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