Original subtitles

In this video we're going to look at IP version for tracing.

I'm going to give you an overview of IP version 4 addresses and explain the basics of provision for

addressing.

From now on I'm going to refer to IP addresses but be a way of please that I'm discussing IP version

4 addresses in this video and not IP version 6 addresses.

We're going to look at an overview of IP addresses what they looked like and how they function.

I'm going to explain the various address classes that you get an IP version 4.

In other words plus A plus B plus C plus D and Class E.

We'll also talk about cyder.

We'll see IDR and how that changes the address classes.

But as a foundation it's important that you understand the 5 address classes A B C D and he will look

at special IP addresses including the loopback address the local broadcast address and other special

addresses.

And lastly I'm going to explain what network mosques do and why they important with regards to IP addressing.

So what is an IP address an IP address is a layer 3 logical address assigned by an administrator.

Unlike MAC addresses which are hard coded or burnt into Network Interface Cards by the manufacturer

an IP address is configured by an administrator.

The IP address may change within a subnet.

For example when using DHP or Dynamic Host Configuration Protocol an IP address resides at a layer 3

in the overside model.

Please refer to the oocyte videos for more details on how the overside model works.

An IP address is used to uniquely identify a device on the network and is used by routers to determine

where that device is.

So a router routes traffic to a destination IP address based on a hierarchy of network and host which

will talk about in a moment.

So once again the IP address uniquely identifies a device in a network in a similar way to how houses

are uniquely identified him Street houses in the street have a unique address.

So for example 10 Oxford Street in the same way a host in a network has a unique identifier on that

network being its IP address.

I'm going to expand on that analogy in the next few minutes.

Every device on Internet has a unique IP address.

So they are millions of IP addresses out there.

And no two devices can have the same IP address for communication on the Internet.

Every device needs a unique IP address and hence the move to IP version 6 these days because of IP version

4 address exhaustion.

So for example you cannot have a device 10 dot 1.1 but one communicating with a another device with

the same IP address that's going to cause a conflict in the network.

Every device on the Internet has its own unique IP address and requires a unique IP address for communication.

Now I will be talking about RAFC 1918 addresses in a moment in that RAFC private IP address as I explained.

So tender at 1.1 that one is an example of a private IP address as specified in our FC 19:18 you know

a lot of organizations today private IP addresses are used internally and then those addresses on nattered

or network address translated onto the Internet.

So when a device with IP address 10 1 1 1 is connected to a public IP address such as 12 to one that

1.1 the public IP address in this case 12 the one at one time one needs to be unique on the Internet.

For now just understand that IP address is on the internet need to be unique from each other network

address translation or Knecht once again is not covered in this video.

But I will be discussing that in the set of CCMA videos.

So be aware that in the real world multiple companies may use my IP address to send out one but one

at one but those addresses are not tied to unique IP addresses.

When those devices in traffic onto the Internet.

Now here's a quick demonstration of some IP addresses.

If I'm paying w w w dot yahoo dot com.

Notice that the domain name is translated to an IP address.

So in this case yahoo dot com is translated by a protocol called DNS or Domain Name Service to an IP

address of 87 dot 2:48 dot 112 dot 181.

DNS is used to convert easy to read names to IP addresses.

It's much easier to remember a simple name such as Yahoo dot com or Cisco dot com or BBC.

It's here to UK rather than having to remember the IP address of those domain names.

As an analogy this is similar to a phone book where we are translating human friendly computer names

to IP addresses.

But what I'd like you to notice is that the IP address of yahoo dot com was resolved and we got an IP

address of 87 to 4 8 1 1 2 181.

I could pick another web site such as HP dot com.

Notice the IP address is translated to 15 from 192 45 139.

Now a lot of Web sites don't permit pings which uses ICMP.

So the request times out.

But notice that the DNS server did resolve HP to come to a 15 address.

Now in a moment I'm going to explain what class A addresses are.

But for this example HP own the 15 class a public address range so anything that starts with 15 in the

first octet belongs to HP.

Here's another example a pink Google dot com notice in this case it resolves to 74 125 233 50.