DNS for IT Girls - How the Internet Works Like Magic

What is DNS?#

DNS (Domain Name System) is like the translator of the internet. It turns human-friendly domain names (web.yourcompany.net) into machine-readable IP addresses.

Think of it like your phone contacts: instead of memorizing phone numbers, you just tap on a name. DNS does the same, but for websites.

Without DNS, you’d have to type 10.0.0.25 instead of facebook.com. Not cute, right? 😅

The Hosts File: The Old-School Hack#

Before DNS, people manually assigned names to IPs using the /etc/hosts file (yeah, ancient times! 😂). But guess what? You can still use this trick today to override DNS settings on your machine!

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10.0.0.5 database

Enter the DNS Server!#

Managing hostnames manually gets messy real quick, so that’s where DNS servers come in! They centralize everything, so instead of keeping a giant hosts file, your system just asks a DNS server for the right IP.

For example, if your company’s internal DNS server is at 10.10.10.1, your laptop will query it whenever it needs to resolve a hostname. If the server doesn’t know the answer, it forwards the request up the chain until it finds the right IP.

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nameserver 10.10.10.1

Subdomains: The DNS Name Tree#

Ever wondered why we have maps.yourcompany.net, mail.yourcompany.net, and drive.yourcompany.net? These are subdomains, and they help organize different services inside a company or website. 🌍✨

Example DNS setup for a company:

• web.yourcompany.net → Main website
• db.yourcompany.net → Database server
• mail.yourcompany.net → Email services

DNS ensures that when users type these names, they are sent to the correct servers. It’s basically the road sign system of the internet! 🚦

DNS Caching: How the Internet Gets Faster#

Every time you visit a website, your system caches (stores) the DNS result so it doesn’t have to ask again. This speeds things up 🚄 but can sometimes cause problems when IPs change.

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ipconfig /flushdns

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sudo systemd-resolve --flush-caches

Public vs Private DNS: Who Controls the Internet?#

If your DNS server doesn’t know an answer, it forwards the request to public DNS servers like:

✅ Google DNS → 8.8.8.8
✅ Cloudflare DNS → 1.1.1.1
✅ OpenDNS → 208.67.222.222

But for internal company networks, private DNS servers keep things secure. For example, if you work at yourcompany.net, you don’t want random strangers resolving your internal servers! 🚨

Recap: DNS is the GPS of the Internet!#

Now you know that DNS is the backbone of the web—it translates names into IPs, manages subdomains, caches results for speed, and allows you to override settings when needed.