Domain configuration is a fundamental skill for every web developer. Whether you're deploying a personal portfolio, SaaS application, or backend API on a VPS, understanding DNS records helps connect your domain name to your server correctly.

In this guide, I’ll explain DNS records, their purpose, and how to configure domains and subdomains for a VPS-hosted application.

📚 What is DNS?

DNS (Domain Name System) is like the internet’s phonebook.

It translates human-readable domain names:

example.com

into machine-readable IP addresses:

192.0.2.1

Without DNS, users would need to remember IP addresses instead of domain names.

🔹 A Record (Address Record)

Purpose

An A record connects a domain directly to an IPv4 address.

When a user visits your domain, DNS uses the A record to find your server’s IP.

Example

Field	Value	Description
Type	A	Address Record
Host	@	Root domain (example.com)
Value	192.0.2.1	Server IP
TTL	3600	Cache time

How it works

example.com → 192.0.2.1 → Your VPS server

Use Case

Connecting your domain to VPS

Hosting website on custom server

Backend API hosting

CNAME Record (Canonical Name Record)

Purpose

A CNAME record aliases one domain to another domain.

It does not point to an IP directly.

Example

Field	Value
Type	CNAME
Host	www
Value	example.com
TTL	3600

How it works

www.example.com → example.com → 192.0.2.1

Use Case

Point subdomains to main domain

Connect domain to external services (Vercel, Netlify, etc.)

🔹 TXT Record (Text Record)

Purpose

TXT records store text information in DNS.

Used for:

Domain verification

Email authentication

Security configuration

Example (SPF Record)

Field	Value
Type	TXT
Host	@
Value	"v=spf1 include:_spf.google.com ~all"
TTL	3600

Use Case

Google Search Console verification

Email setup (Gmail, Outlook)

Prevent email spoofing

🔹 NS Record (Name Server)

Purpose

NS records tell the internet which DNS server manages your domain.

Example

ns1.hostinger.com
ns2.hostinger.com

These servers contain your DNS records.

🔹 What is TTL in DNS?

TTL (Time To Live) defines how long DNS records are cached.

Example:

TTL = 3600

Means DNS will cache for:

3600 seconds = 1 hour

Common TTL Values

TTL	Duration	Use Case
60	1 minute	Testing
300	5 minutes	CDN
3600	1 hour	Default
86400	1 day	Stable websites

⚖️ A Record vs CNAME Record

Feature	A Record	CNAME
Points to	IP address	Domain
Speed	Faster	Slightly slower
Root domain support	Yes	No
Flexibility	Less flexible	More flexible

VPS Domain Configuration Example

Suppose you purchased a VPS and want to host multiple websites.

Setup

Domain:

aminul.com

VPS IP:

79.87.90.90

Subdomains:

www.aminul.com
portal.aminul.com
server.aminul.com

Option 1: Using A Records

Type	Host	Value	TTL
A	@	79.87.90.90	3600
A	www	79.87.90.90	3600
A	portal	79.87.90.90	3600
A	server	79.87.90.90	3600

Option 2: Using CNAME (Recommended)

Type	Host	Value	TTL
A	@	79.87.90.90	3600
CNAME	www	aminul.com	3600
CNAME	portal	aminul.com	3600
CNAME	server	aminul.com	3600

This setup is easier to maintain.

Only update one A record if server IP changes.