Blog 10 Understanding DNS to Inodes: From Browsers to Backends

🔍 What Is DNS? Why Should DevOps Even Care?

📘 Explained Like You’re 15!

✍️ By: Kalyan Kalavena | DevSecOps in the Making

🌐 Human Names vs Machine Numbers

When you type facebook.com, your browser magically opens Facebook.

But under the hood? It’s just finding a real server with an IP address like 157.240.22.35.

Humans = love names
Computers = need numbers

That’s where DNS (Domain Name System) steps in — it's the internet’s phonebook.

facebook.com → DNS → 157.240.22.35 → BOOM, Facebook Loads!

⚙️ How DNS Actually Works (Real Flow)

You visit:

mysql.daws82s.online

Here’s the backend magic:

• Resolver asks, “Where’s this domain?”
• DNS checks .online → asks daws82s.online nameserver
• Nameserver responds: “Here’s mysql's IP”
• Browser hits the IP → Site loads 🔥

🏠 What’s an IP Address?

Every server = house
IP = address

Two types:

Type	Changes When?
Public IP	Restart cloud instance
Private IP	Recreate VM

💡 If IP changes, update backend configs & restart services:

sudo systemctl daemon-reexec
sudo systemctl restart backend

🧑‍⚖️ Who Owns DNS?

ICANN = The Internet Boss
(Internet Corporation for Assigned Names and Numbers)

They manage:

• 🌐 Country TLDs (.in, .uk)
• 🏛️ Org domains (.edu, .gov)
• 💡 Custom ones like .ai, .online, .telugu

Want joindevops.telugu? Gotta go through ICANN!

🛒 What Happens When You Buy a Domain?

You buy daws82s.online from GoDaddy/Hostinger:

• Host tells .online registry (Radix) you own it
• You assign Nameservers
• Add A Records to map domains to IPs

mysql.daws82s.online → 13.212.56.78

Done. DNS knows where to send traffic!

📄 Common DNS Records

Type	Purpose
A	Domain → IP
CNAME	Domain → Another domain
MX	Mail servers
TXT	Verification, SPF, etc.
NS	Nameservers
SOA	Domain ownership + config metadata

🛠️ Real DevOps Example (Systemd + Nginx)

Systemd:

[Service]
Environment=DB_HOST="mysql.daws81s.online"
ExecStart=/bin/node /app/index.js

Nginx Proxy:

location /api/ {
  proxy_pass http://backend.daws81s.online:8080/;
}

Visit:

http://daws81s.online/api/transaction

→ Proxies to backend API!

🔬 Bonus: Inodes, Symlinks & Hardlinks

🧬 Inode = File's DNA

Stores: permissions, timestamps, size, etc.

🔗 Symlink

• Shortcut to file
• Different inode
• Breaks if original file is deleted

lrwxrwxrwx 1 root root 11 Dec 26 03:10 DbConfig1.js -> DbConfig.js

🪢 Hardlink

• Same inode
• Works even if original is deleted
• Not for directories

ls -i filename  # Get inode
find / -inum <inode>  # Find all hardlinks

🎯 Final Takeaway

DNS is the invisible butler of the internet.
Inodes, links, and configs? They're your DevOps gears.

💥 Mastering this stuff makes you a builder — not just a button-pusher.

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👨‍💻 Written by: Kalyan Kalavena
🛡️ DevSecOps in the Making | Terminal to Terraform

📢 All rights reserved. Kalyan .