IP Addresses

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來自 Google 的課程

The Bits and Bytes of Computer Networking

3756 個評分

Google

The Bits and Bytes of Computer Networking

3756 個評分

課程 2（共 5 門，Specialization Google IT Support Professional Certificate）

This course is designed to provide a full overview of computer networking. In this course, we’ll cover everything from the fundamentals of modern networking technologies and protocols to practical applications and network troubleshooting. By the end of this course, you’ll be able to: - describe computer networks in terms of a five-layer model. - understand all of the standard protocols involved with TCP/IP communications. - grasp powerful network troubleshooting tools and techniques. - learn network services like DNS and DHCP that help make computer networks run. Except as otherwise noted, the contents on this site are licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

從本節課中

The Network Layer

In the second week of this course, we'll explore the network layer in more depth. We'll learn about the IP addressing scheme and how subnetting works. We'll explore how encapsulation works and how protocols such as ARP allow different layers of the network to communicate. We'll also cover the basics of routing, routing protocols, and how the Internet works. By the end of this module, you'll be able to describe the IP addressing scheme, understand how subnetting works, perform binary math to describe subnets, and understand how the Internet works.

The Network Layer1:23

IP Addresses2:46

IP Datagrams and Encapsulation6:42

IP Address Classes3:57

Address Resolution Protocol2:08

Sergio Path1:35

與講師見面

Google

IP addresses are 32-bit long numbers made up of 4 octets, and

each octet is normally described in decimal numbers.

8 bits of data, or a single octet,

can represent all decimal numbers from 0 to 255.

For example, 12.34.56.78 is a valid IP address.

But 123.456.789.100 would not be,

because it has numbers larger than could be represented by 8 bits.

This format is known as dotted decimal notation.

We'll deep dive into how some of this works in an upcoming lesson

about subnetting.

The important thing to know for now is that IP addresses are distributed in large

sections to various organizations and companies,

instead of being determined by hardware vendors.

This means that IP addresses are more hierarchical, and

easier to store data about than physical addresses are.

Think of IBM, which owns every single IP that has the number 9 as the first octet.

At a very high level, this means that if an Internet router needs to figure out

where to send a data packet intended for the IP address 9.0.0.1,

that router only has to know to get it to one of IBM's routers.

That router can handle the rest of the delivery process from there.

It's important to call out that IP addresses belong to the networks,

not the devices attached to those networks.

So your laptop will always have the same MAC address, no matter where you use it.

But it'll have a different IP address assigned to it at an Internet cafe than

it would when you're at home.

The LAN at the Internet cafe or the LAN at your house would each be individually

responsible for handing out an IP address to your laptop if you power it on there.

On a day-to-day basis,

getting an IP address is usually a pretty invisible process.

You'll learn more about some of the technologies at play in a later lesson.

For now, remember that on many modern networks, you can connect a new device.

And an IP address will be assigned to it automatically

through a technology known as Dynamic Host Configuration Protocol.

An IP address assigned this way is known as a dynamic IP address.

The opposite of this is known as a static IP address,

which must be configured on a node, manually.

In most cases, static IP addresses are reserved for servers and

network devices, while dynamic IP addresses are reserved for clients.

But there are certainly situations where this might not be true.

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