The study didn't do a lot to explain decimal to binary conversions, so I just wanted to add this as an extension. I hope you guys don't mind.
The eight bit binary place values look something like this:
These are read from right to left and work in the same way as decimal place values. The major exception is that each place value to the left is equal to 2 times its preceding value. Let me show you what I mean. The first bit's place value is equal to 1. The second bit's place value is equal to 2 (2x1=2) The third is equal to 4 (2x2=4). The fourth is equal to 8 (2x4=8). The fifth is equal to 16 (2x8=16). The sixth is equal to 32 (2x16=32). The seventh is equal to 64 (2x32=64). And the eighth is equal to 128 (2x64=128).
Now remember the ip address in the tutorial above (192.168.0.1)? The way they converted that address to binary (11000000.10101000.00000000.00000001) goes like this:
1.) First, you'll notice that there are four sets of numbers seperated by dots. Each set of these numbers are called "Octets
". 192 will be the fourth octet. 168 will be the third octet. 0 is the second octet. And 1 is the first octet. Remember that we're counting from right to left. The reason they are called Octets is because each of these decimal values is made up of eight binary values. So 8bits=1octet.
2.) Now we're going to work each octet one at a time starting with the first. All you need to remember is the chart above. Take the first octet (1) and look back at the chart. Start at the last binary place value (128) and ask yourself "Is 1 devisible by 128"? The answer is No! So we place a zero in that place value.
3.) Now look at the next place value in the chart (64). Ask yourself the same question, "Is 1 devisible by 64"? No! So we put a zero in that place value. Remember that a binary zero is equivalent to a "NO
" statement (no, false, off, etc.,etc.)
4.) Now look at the next place value (32). Is 1 devisible by 32? No! So it gets a zero.
5.) What about the next place value (16). No? Then it gets a zero.
6.) And is 1 devisible by 8? Nope! It gets a zero.
7.) 4? Nope! It gets a zero.
8.) 2? Nope! It gets a zero.
9.) What about the one place value? Is 1 devisible by 1? Why yes it is!!!!
So we put a one in its place.
So for the first octet (1) we get the binary value of 00000001. Now for the second octet (0) we just get all zeros 00000000. For the third octet (168) we'll use the same process, but this time watch what happens. 168 is devisible by 128, so we put a one in that place value and keep working down the chart using the remainder, which is 40 (168 - 128=40). 40 isn't devisible by 64, so we put a zero in that place value and move down the chart. 40 is devisible by 32, so we put a one in that place value and move down the chart using the remainder of 8. 8 is'nt devisible by 16, so we put a zero in that place value and move on down the chart. Ah Ha! 8 is devisible by 8 leaving us with no remainders. So we place a one in that place value and zeros in the remaining place values because we have nothing left to work with. So the binary equivalent of 168 will be 10101000. Now you do the math for the last octet (192).
To reverse the process, simply add together all place values that have a binary one. For exmple 10101000 has a one in the 128 place value, a one in the 32 place value and a one in the 8 place value. 128+32+8=168!
Now you know how to convert decimal ip addresses to their binary equivalents and visa-versa.
Hope this helps and as always...Happy Hacking!!!