---
title: "Addresses on a Network: Naming a Machine and Naming a Page"
description: "For one machine to send data to another it needs an address that is unique on the network. A web address is a different kind of name, one that has to be looked up and turned into a machine address bef"
canonical: https://lightmysky.com/learn/computing/addresses-on-a-network-naming-a-machine-and-naming-a-page-mt_tGgw0Vhd8b
source: https://lightmysky.com/learn/computing/addresses-on-a-network-naming-a-machine-and-naming-a-page-mt_tGgw0Vhd8b.md
retrieved: 2026-09-12
---

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# Addresses on a Network: Naming a Machine and Naming a Page

For one machine to send data to another it needs an address that is unique on the network. A web address is a different kind of name, one that has to be looked up and turned into a machine address before anything can be sent.

Subject: Computing · Area: Computing Fundamentals · Ages 13 to 14
Page: https://lightmysky.com/learn/computing/addresses-on-a-network-naming-a-machine-and-naming-a-page-mt_tGgw0Vhd8b

## Ready when they can

- Say what an address has to promise for a message to arrive, and why two machines on one network cannot share one
- Break a web address into the part naming a machine and the part naming a page on it
- Describe why the name has to be looked up first, and what happens if the lookup fails

## Lesson: Number for the machine, name for the page

Every device on a network needs an address that is unique. Just as homes need mailing addresses to receive mail, computers need an IP address to receive messages. A message must carry the other computer's address, or the network has no idea where it should go.

**Example.** An IPv4 address looks like 74.125.20.113: four numbers, each from 0 to 255. The first part names the network and the last part names the single machine on it, a bit like a phone number with a country code and an area code. Try typing such a number into a browser. It still arrives.

A web address is a different kind of name. It names a machine plus a page on it, in words humans like. Before anything can be sent, that name must be looked up and turned into the machine's number. If two machines shared one address, a message could land on either or get lost.

**Tip.** If the lookup fails, nothing is sent, because a name without a number points nowhere. So when a page will not load, the name never became an address. The machine part and the page part only work after the lookup succeeds.

**Recap.** Machines send to unique numbers, and web names must become numbers first.

## Practice

8 questions on this page, each with its working shown.

## Needs first

- [Networks and the Internet](https://lightmysky.com/learn/computing/networks-and-the-internet-mt_JmrMg6v8V_)

## Opens up

- [Packets and Protocols on a Network](https://lightmysky.com/learn/computing/packets-and-protocols-on-a-network-mt_IffXVDtfLX)