---
title: The Online Address Book
description: This video focuses on the first prerequisite for using a tunnel, a domain name. It uses the metaphor of an online address book to explain DNS and how Cloudflare manages your domain.
image: https://developers.cloudflare.com/cf-twitter-card.png
---

> Documentation Index  
> Fetch the complete documentation index at: https://developers.cloudflare.com/videos/llms.txt  
> Use this file to discover all available pages before exploring further. 

[Skip to content](#%5Ftop) 

# The Online Address Book

This video focuses on the first prerequisite for using a tunnel, a domain name. It uses the metaphor of an online address book to explain DNS and how Cloudflare manages your domain.

```json
{"@context":"https://schema.org","@type":"TechArticle","@id":"https://developers.cloudflare.com/videos/the-online-address-book/#page","headline":"The Online Address Book | Cloudflare Docs","description":"This video focuses on the first prerequisite for using a tunnel, a domain name. It uses the metaphor of an online address book to explain DNS and how Cloudflare manages your domain.","url":"https://developers.cloudflare.com/videos/the-online-address-book/","inLanguage":"en","image":"https://developers.cloudflare.com/cf-twitter-card.png","publisher":{"@type":"Organization","name":"Cloudflare","url":"https://www.cloudflare.com/"},"isPartOf":{"@type":"WebSite","@id":"https://developers.cloudflare.com/#website","name":"Cloudflare Docs","url":"https://developers.cloudflare.com/"}}
```