All language subtitles for 4. IPv4 Address format (Street Analogy) and Address Classes

So once again the
format of an IP address in

this case IP version 4
is a 32 bit binary number.

It's divided into four parts or four octets which are 8 pets or one byte in size.

So an IP address could be written as follows in binary in dotted decimal notation or it could be written

as follows.

Ducted decimal notation.

So just to summarize it say for byte number or 32 bit number typically written in dotted decimal notation.

But be aware that it's actually a binary address of 32 bits.

Please refer to the binary videos.

If you're not sure about the formatting or conversion of binary to decimal and back again and octet

is 8 binary bets all one byte one byte equates to eight binary bits.

So no provision for dress consists of four octets such as extra X to add extra X where X is an octet

or 8 bits or one byte.

Now using our street analogy again it's possible to have the same house number on different streets.

So house one could be an Oxford Street as well as Cambridge Street.

House Number One should just not appear twice on the same street.

But number one is permitted on different streets in the same way here.

It's possible to have number one on Network 10 but one dog 1.0 slash 24 as well as number one on network

19
12:48 1.0 slushed 24 the same number can appear on different networks.

I'll explain this next 24 in a moment.

When we discuss network mosques but in this example we have network up one at 1.0 and told at one point

1.0 and it's possible to have multiple devices with the host portion of the IP address set to one the

same host portion can appear twice as I'm in this example or many times in a network or the internet.

As long as the network portion is different now one thing you'll learn about networking is that things

are constantly changing across classes or classful networks were used in the Internet from 1981 until

the introduction of classless into domain routing in 1993 which is commonly known as cyder or C IDR.

Now prior to 1993 address classes were used to divide the IP version 4 address space into five address

classes.

The three that we are going to concentrate on here are Class A B and C which are used for any cost traffic

plus D is used for multicast and class-C is reserved for future or experimental purposes.

Classes have been superseded in IP version 6 IP version 6 and does not use address classes and in IP

version 4 address classes have been replaced with cyder.

So the different classes of addresses a B and C were used to accomodate different sizes of networks

which aided in the classification of those networks.

So as an example a classful address supports about 16 million IP addresses.

So once again we had plus a b and c..

These have been replaced with superseded by cyder.

We'll see IDR and address classes such as A B and C were determined and then allocated by the owner

or internet assigned numbers or 30.

This format is not used entirely in its original format.

Today he has an entry on Wikipedia showing the list of class addresses.

So each class a address has approximately 16 million IP addresses.

And if we scroll down the list we can see various examples.

AT&T have 12 Xerox 13 HP 15 Dec. 16 so 15 and 16 are now owned by HP.

Apple has 17 MIT 18 Ford 19 and so forth and so on.

So notice as an example Apple own 17.00 doats arrow slash 8 Apple have 16 odd million public IP addresses

that are part of the Class A address.

So in the original IP address format across a address consists of eight network bits and 24 host bits.

Hence it's written as shaped denoting eight network bets.

Now this was fine when the Internet was small but it quickly became a limiting factor and thus multiple

addresses were introduced with a different size and network portions.

Hence we have class a class B and class C addresses.

Please note once again that class full addresses were replaced in 1993 with plotless into domain routing

or C ID are also called cyder.

However you may still come across commands that use the classful address format.

An example of that is the net work command within writing protocols.

So as an example if you use the network command on a rope routing process the command is written in

a class full format.

It's also worth knowing a bit of the history and understanding why we have problems with a lack of IP

addressing today.

Hence it's worth your learning about potful addresses for completeness.

The breaking up of addresses was originally used to try and save or conserv IP addresses but did not

work in its original format and thus was expanded and changed by cyder well-explained side in a moment.

Let's first look at the various address classes in more detail.