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Course outline
  1. 01How a computer works
    1. 1.1What is a computer?(completed)
    2. 1.2The CPU: the brain(completed)
    3. 1.3Memory: RAM vs storage(completed)
    4. 1.4How the CPU and memory work together(completed)
    5. 1.5What happens when you turn on a computer(completed)
  2. 02How the Internet works
    1. 2.1What is the Internet?(completed)
    2. 2.2Addresses and names: IP and DNS(completed)
    3. 2.3Packets: how information travels(completed)
    4. 2.4Client and server: opening a website(completed)
    5. 2.5Inside a busy server(completed)
    6. 2.6Why this matters for AI(completed)
  3. 03Introducing the GPU
    1. 3.1What is a GPU?(completed)
    2. 3.2CPU vs GPU(completed)
    3. 3.3The GPU's own memory: VRAM(completed)
    4. 3.4How the CPU and GPU work together(completed)
    5. 3.5Why GPUs suit AI(completed)
  4. 04Tensors and models
    1. 4.1What is a tensor?soon
    2. 4.2What is an AI model?soon
    3. 4.3Training vs inferencesoon
  5. 05Splitting work across GPUs
    1. 5.1Why split work across GPUs?soon
    2. 5.2Data parallelismsoon
    3. 5.3Tensor parallelismsoon
    4. 5.4Pipeline parallelismsoon
    5. 5.5Expert parallelismsoon
    6. 5.6Which to use whensoon
  6. 06Serving LLMs with vLLM
    1. 6.1What is LLM serving?soon
    2. 6.2Meet vLLMsoon
    3. 6.3Serving a model with vLLMsoon

Lesson 2.2

Addresses and names: IP and DNS

How computers find each other: number addresses, and the address book that turns names into numbers.

beginner 3 min readChecked

In one line

Every device on the Internet has a number called an IP address, and DNS is the address book that turns names like example.com into those numbers.

Real-life analogy

To deliver food to a customer, the restaurant needs their street address. “Priya’s house” is not enough for the driver; they need “12 Lake Road”.

On the Internet, the street address is the IP address, a number like 192.0.2.172.

But you do not remember the address of every friend. You look up their name in your phone’s contacts. That contacts list is DNS: you give it a name, it gives you back the number.

Where the comparison stops working: a house address almost never changes. The IP address behind a website can change, for example when it moves to a new server. That is fine, because you only ever type the name, and DNS always gives you the current number.

Diagram

YourbrowserDNS(the address book)Web server192.0.2.1721. Where is example.com?2. It is at 192.0.2.1723. connect to that numberNames are for people.Numbers (IP addresses)are for computers.DNS turns one intothe other.
DNS turns a name you can remember into the number (IP address) computers use.

Step by step

In the last lesson, we said routers pass messages “one step closer to where they need to go”. But how does a router know where a message needs to go?

IP addresses: numbers for computers

Every device on a network gets an IP address. IP stands for Internet Protocol, the shared set of rules for addressing and delivering messages on the Internet.

A common kind of IP address (called IPv4) looks like four numbers separated by dots, for example 192.0.2.172. Every message carries the IP address of where it is going and where it came from, so routers can pass it along and the reply can find its way back.

The problem with numbers

Could you remember the IP address of every website you visit? Of course not. And the number behind a website can change when it moves to a different server.

People need names. Computers need numbers. Something has to connect the two.

DNS: the Internet’s address book

That something is DNS, the Domain Name System. A domain name is a website’s name, such as example.com or learn.naveenops.com.

Here is what happens when you type a name into your browser:

  1. Your browser asks DNS: “Where is example.com?”
  2. DNS looks it up and answers with the IP address, for example 192.0.2.172.
  3. Your browser now connects to that number.

All of this usually takes a tiny fraction of a second, and you never see it.

Who runs DNS?

DNS is not one big computer. It is a system of many servers around the world, each responsible for its own part of the names. Your device (or your Internet provider) asks them on your behalf and usually remembers recent answers, so it does not have to ask again every time.

Key takeaways

  • Every device on the Internet has an IP address: a number that tells messages where to go.
  • Messages carry both the destination and the sender’s address.
  • People use names; computers use numbers.
  • DNS is the address book that turns a name into an IP address.

Recap: a delivery driver needs a street address, and you find it by looking up a name in your contacts. Computers need an IP address, and they find it by asking DNS.

Now you understand what an IP address is and what DNS does. Next, we will see how a message actually travels: in small pieces called packets.

Quick check

Pick an answer, then press Check answer. Nothing is recorded.

  1. What is an IP address?
  2. You type learn.naveenops.com. What is the first job of DNS?
  3. Why do we have names at all, if computers use numbers?

Sources

This lesson was checked against these pages.

  1. IP Address (glossary) · MDN Web Docs
  2. DNS (glossary) · MDN Web Docs
  3. How does the Internet work? · MDN Web Docs
  4. How the web works · MDN Web Docs
  5. RFC 1034: Domain Names, Concepts and Facilities · IETF
  6. RFC 5737: IPv4 Address Blocks Reserved for Documentation · IETF