Nginx + DNS Explained for DevOps Beginners (With Real-World Examples)
If you are learning DevOps, two topics will come again and again:
✅ Nginx (Web server + Reverse Proxy)
✅ DNS (Domain → IP resolution)
Today I learned both, and in this blog I’m sharing my notes in a clean way with extra real-world understanding, so it can help other DevOps learners too.
👋 If you found this article helpful and want to follow my DevOps learning journey,
connect with me on LinkedIn 👉 RamuChelloju
1) What is Nginx?
Nginx is a high-performance web server used to serve static files like:
HTML
CSS
JavaScript
Images
It can also be used as:
✅ Reverse Proxy
✅ Load Balancer
✅ API Gateway (basic)
✅ TLS/SSL termination
Real use in production:
Most companies use Nginx to serve frontend and route requests to backend applications (Node.js, Java, Python, etc.).
2) Nginx vs Apache (Quick Difference)
Both are web servers, but:
Apache
Process/thread-based
Good for dynamic modules
Older and widely used
Nginx
Event-driven and lightweight
Handles high traffic efficiently
Excellent for reverse proxy and load balancing
DevOps takeaway:
Nginx is very common in microservices and modern architectures.
3) What is a Proxy?
A proxy is a middle server that sits between client and server.
✅ Forward Proxy (Client Side Proxy)
Forward proxy works on the client side.
📌 Use cases:
VPN
Blocking websites
Monitoring user traffic
Hiding client identity
Example:
Client → Forward Proxy → Internet
✅ Reverse Proxy (Server Side Proxy)
Reverse proxy works on the server side.
📌 Use cases:
Hiding backend server IP
Routing API requests to backend
Load balancing
Security control
Example:
Client → Nginx (Reverse Proxy) → Backend App
4) Nginx Reverse Proxy Example (Real Scenario)
Assume we have:
Frontend is running on Nginx
Backend Node.js is running on port 8080
Frontend URL:
http://frontend-server
Backend API:
http://backend-server:8080
Instead of exposing backend to public, we do reverse proxy in Nginx like this:
location /api/ {
proxy_pass http://backend-server:8080/;
}
Now the user will access backend like:
✅ http://frontend-server/api/
And Nginx will forward it internally to backend.
5) Important Nginx Paths (Linux)
These paths are important for every DevOps learner:
✅ Configuration folder
/etc/nginx/
✅ Default configs (commonly used)
/etc/nginx/default.d/
Example:
/etc/nginx/default.d/expense.conf
✅ Default web root (static files location)
/usr/share/nginx/html/
✅ Nginx logs
/var/log/nginx/
access.logerror.log
6) What is DNS Resolver?
DNS Resolver is responsible for converting:
✅ Domain name → IP Address
Example:
google.com → 142.250.xx.xx
Whenever we type a website URL, DNS helps to find the correct server IP.
7) How DNS Works (Step-by-Step Flow)
When you open a domain in browser, DNS resolution happens in this order:
✅ DNS Resolution Flow
Browser Cache
OS Cache
ISP DNS Resolver Cache
Root Servers
TLD Servers
Authoritative Nameserver
Returns IP address back to browser
8) Root Servers (Important Concept)
There are 13 Root Servers worldwide (logical root server identities).
Root servers do not store every domain record, but they know where to find:
✅ TLD information (like .com, .in, .net)
Root servers are part of DNS root zone and are under ICANN management.
9) What is TLD?
TLD = Top Level Domain
Examples:
.com.in.net.org.us.uk.edu.ai.shop.online
Example:
In example.com
example= domain name.com= TLD
10) What is a Domain Registrar?
A Domain Registrar is a company where we can buy and manage domains.
Examples:
GoDaddy
Hostinger
Porkbun
AWS Route53 (Domain registration + DNS)
📌 You can also transfer your domain from one registrar to another.
11) Domain Purchase Flow (What Happens in Background?)
Let’s say you buy:
✅ ramu.com
Steps:
You check domain availability in registrar
Registrar checks with the TLD registry
Payment completed → domain gets assigned to buyer
Registrar updates domain ownership and details
You configure DNS records like A record
Changes propagate based on TTL
12) DNS Records You Must Know
✅ A Record
Maps domain to IPv4 address
Example:
ramu.com → 54.12.34.56
✅ NS Record (Name Server Record)
Tells which DNS servers manage the domain.
Example:
ns-123.awsdns-45.com
ns-456.awsdns-12.net
✅ TTL (Time To Live)
TTL means how long the DNS response is cached.
Example:
- TTL = 3600 seconds = 1 hour
13) TTL Practical Real-World Tip
If you are changing IP address (migration / deployment):
✅ Keep TTL low (like 60 seconds)
So DNS changes update faster.
After everything is stable:
✅ Set TTL back to 3600s (1 hour)
14) AWS Route53 (Easy Explanation)
Route53 is AWS DNS service.
Typical flow:
Create Public Hosted Zone in Route53
Route53 gives you NS records
Update those NS records at your domain registrar
Now Route53 becomes responsible for your DNS
After that you can create:
A record
CNAME
TXT
etc.
15) Useful DNS Command
To check domain resolves correctly:
nslookup yourdomain.com
Example:
nslookup servicowiz.in
Output will show the IP address.
✅ Quick Revision Summary
Nginx
Web server for static content
Reverse proxy for backend services
Config in
/etc/nginx/Web root
/usr/share/nginx/html/
DNS
Converts domain → IP
Uses caching (browser → OS → ISP)
Root → TLD → Authoritative NS
A record maps domain → IP
TTL controls caching duration
🎯 Interview Questions (Must Prepare)
✅ What is Nginx and why is it used?
✅ Difference between forward proxy and reverse proxy
✅ Explain DNS resolution flow step-by-step
✅ What are root servers and how many are there?
✅ What is TLD?
✅ What is a domain registrar?
✅ What is A record and NS record?
✅ What is TTL and why we change it?
✅ Final Thoughts
Learning Nginx + DNS gave me clear understanding of how real web applications work:
Frontend served by Nginx
Backend routed via reverse proxy
Domains mapped using DNS records
This is a strong foundation for DevOps and Cloud.
