I'm going to talk about IP addresses in a lot of detail later.
But let's look at an example on this phone and you'll be able to do something similar on an Android
device or Windows PC and so forth.
I'm going to go to settings.
I'm going to look at the information about my wireless network and what I can see here is that my IP
address was configured automatically.
Basically a server allocated an IP address to my phone.
That's very typical of network so using what's called DHCP or Dynamic Host Configuration Protocol a
server allocates an IP address to your device.
In this example, my IP address on the phone is 192.168.172
Now that is a 4 octet IP address IPv4 octet 8 binary values.
Hopefully, it makes a bit more sense now 192 in decimal equates to 1100 followed by 4 0s.
So 11 and 6 binary 0s is the equivalent of 192 in decimal.
So we've got an 8 bit binary number 192 followed by a dot followed by another 8 bit binary number.
In this example 168 followed by another number 1 followed by the last number 72, 4 octets or 4 binary
each gives us an IPv4 address with the length of 32 bits, 8 plus 8 plus 8 plus 8 32
bits in binary.
So 192 is an 8-bit binary number which equates to 1 1 followed by 6 0s.
We could do something similar for 168.
We could work out what that is in binary. 1 is fairly simple it's 7 binary 0s followed by a
binary one gives me decimal 1 and then we've got 72.
We've also got a subnet mask subnet masks become very important to determine if our host is on the same
subnet as you.
We'll talk about that in more detail in the subnetting section but hopefully, now you can recognize 255
255 is eight binary ones so you've got eight binary ones 255 and another eight binary ones 255 third
255 is equivalent to eight binary ones.
And then we've got eight binary zeros 32 that subnet mask once again.
So for octet or for groupings if you like of binary ones and zeros which are eight bits in size then
we've got a default gateway 1 9 2 1 6 8 1 249.
That is an example of an IP version for dress with its subnet mask and default gateway.
In this example on my phone you could do something similar on a computer.
So in my example I could go to my wireless connection on my P.C. open network preferences and what I
can see here is my Wi-Fi connection on this laptop or MacBook in this case has an IP address of 10 0
0 2.
If I go to advanced DCP IP PCV IP is the protocol that we're using IP version 4 is the IP version that
we're using here we can see IP addresses 10 0 0 2 subnet mask 255 255 255 0 Rodda is 10 0 0 1 IP version
4 address is an address used to uniquely identify a device on an IP version for network we have what
are called IP version for addresses which would look something like this and then we have IP version
6 addresses don't worry about this at the moment but we could have an IP version 6 address that looks
something like this so we won't worry about HPV 6 for the moment.
My provision for is for --.
In other words four times eight.
That's an IP version 4 dress so each value in octet is 8 bits.
Or as an analogy once again 8 cables in the range 0 to 255.
So if we looked at 10 as an IP address 10 looks like this and I'll explain that in more detail in a
moment.
129 looks like this.
Sixteen looks like this.
And 123 looks like this.
We can write the IP address as a decimal IP address a dotted decimal.
That's the most common way to write it but devices use binary.
When you create an access list or do something where you need to permit or deny traffic you're going
to want to think in binary.
Have a look at the binary to understand what's going on.
Devices such as Rodders and firewalls use binary to determine what's permitted or denied.
Okay so here's our example.
We've got 10.
Are you able to work out why it equals this.
Again pause the video if you want more time to work it out for yourself.
But here's the answer.
Using our table this is what the binary number looks like for zeros followed by one followed by binary
zero followed by one followed by binary zero.
Now to get to 10 10 minus 128 would be a negative number.
So it wouldn't be this minus 64 is a negative number.
Wouldn't be that wouldn't be that wouldn't be that but 10 minus eight gives us two so eight plus two
like that equals ten which means we set this bit on and this but on.
Remember this is equal to two to the power of three.
So two states three cables equals eight.
Yeah we've got two states one cable.
Decimal equivalent is two.
So this in binary is equal to 10 in decimal.
Now I'm hoping that makes sense.
I going to do a few more examples now.
So we're going to look at one twenty nine as an example.
If you want a whole bunch of examples have a look at those quiz questions that I have on my website
but feel free to ask questions if you struggling or if you need me to explain this a different way.
So looking at 129 129 minus 128 gives us 1.
So this slide is actually wrong.
This should be a zero because one hundred and twenty nine minus 128 gives us 1.
It doesn't allow us to minus 64 and still have a positive number.
So 128 plus one equals 129.
So this slide is actually wrong.
Let me update it right now because that should be 1 followed by six zeros and a 1 and this should be
1 followed by six zeros and a 1 128 plus one equals 129 definitely not plus 64.
Okay so that looks better 128 plus one equals 129.
So that's the binary equivalent of 129 nine.
You could always use a calculator once again to check your work.
So 129 in decimal equals that in binary in the exam once again you don't have access to a calculator
so you'll need to know this stuff.
Sixteen is fairly easy.
Sixteen is just this binary but so that's what sixteen looks like in binary.
That's what it looks like in decimal.
And then we've got 123 now 123 minus 128 would be less than zero so it's not equal to that but 123 minus
64 equals fifty nine.
So in other words we'll set this value on fifty nine minus thirty two equals twenty seven so that that
will be set on twenty seven is greater than sixteen so we'll set this button on twenty seven minus sixteen
gives us eleven that's greater than eight so we'll set this but on eleven minus eight gives us three
three minus four is a negative number so that but to set off but three minus two equals one so that
but set on and so is this but to give us zero.
So 123 looks like that in binary it's sixty four plus thirty two plus sixteen plus a plus two plus one
equals 123 binary value a decimal value I don't know how easy you found that a lot of this depends on
how good your basic arithmetic is that's obviously a lot easier and that's a lot easier than working
out 123 but the principle applies same principle applies Okay so if you want some unlimited tests you
can go to David Bumble dot com and go to free quizzes there's a binary two decimal quiz as well as a
decimal to binary quiz these are unlimited quizzes they'll just ask you over and over again what are
the values all Okay so that wraps up the binary section I've added some quizzes to the course but once
again you could use those online quizzes if you prefer it's important that you know how to work with
binary it can be quite boring but it's a fundamental building block that you need to know to be able
to work in the real world as well as pass the CCMA exam.