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

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

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addressing.

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From now on, I'm going to refer to IP addresses, but be aware, please, that I'm discussing IP version

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for addresses in this video and not IP version six addresses.

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

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

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In other words, class A, class B, class C, clause D and class E.

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We'll also talk about CIDR or CIDR and how that changes the address classes.

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But as a foundation, it's important that you understand the five address classes, ABC, D and E.

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We'll look at special IP addresses, including the loopback address, the local broadcast address and

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other special addresses.

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And lastly, I'm going to explain what network mosques do and why they are important with regards to

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IP addressing.

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So what is an IP address?

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An IP address is a layer three logical address assigned by an administrator.

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Unlike MAC addresses, which are hard coded or burnt into network interface cards by the manufacturer,

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an IP address is configured by an administrator.

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The IP address may change within a subnet.

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For example, when using DHCP or dynamic host configuration protocol, an IP address resides at a layer

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three in the OCI model.

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

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

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where that device is.

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

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we'll talk about in a moment.

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

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are uniquely identified in a street.

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Houses in the street have a unique address.

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So, for example, ten Oxford Street, in the same way, a host in a network has a unique identifier

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on that network being its IP address.

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

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Every device on the Internet has a unique IP address, so there are millions of IP addresses out there

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

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

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version for address exhaustion.

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So for example, you cannot have a device 10.1, 1.1 communicating with another device with the same

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

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

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Now I will be talking about RFC 1918 addresses in a moment in that RFC private IP addresses are explained.

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So ten .1.1.1 is an example of a private IP address as specified in RFC 1918.

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In a lot of organizations today, private IP addresses are used internally and then those addresses

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are netted or network address translated onto the internet.

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So when a device with IP address ten 111 is noted to a public IP address such as 12 at one point, 1.1,

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the public IP address in this case, 12 .1.1.1 needs to be unique on the internet for now.

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Just understand that IP addresses on the internet need to be unique from each other.

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Network address, translation or NAT once again is not covered in this video, but I will be discussing

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that in the set of CNA videos.

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So be aware that in the real world multiple companies may use IP address 10.1 1.1.

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But those addresses are netted to unique IP addresses when those devices send traffic onto the Internet.

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

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If I ping w WW dot yahoo.com, notice that the domain name is translated to an IP address.

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So in this case, yahoo.com is translated by a protocol called DNS or domain name service to an IP address

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of 87.248 112.1 81.

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

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It's much easier to remember a simple name such as Yahoo.com or Cisco or BBC.co.uk, rather than having

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to remember the IP address of those domain names.

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

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to IP addresses.

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

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of 80 7248112 181.

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I could ping another website such as abc.com.

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Notice the IP address is translated to 15 one 9245 139.

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Now a lot of websites don't permit pings, which uses ICMP, so the request times out.

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But notice that the DNS server did resolve App.com to a 15 address.

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

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But for this example, HP own the 15 class a public address range.

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So anything that starts with 15 in the first octet belongs to HP.

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Here's another example.

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I'll ping google.com.

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Notice in this case it resolves to 74 125 to 3350.