What is DNS, and DNS Record Types | How DNS works
What is DNS?
The Domain Name System is the phonebook of the Internet. Users access information online through domain names such as indiatimes.com or epson.com. A web browser communicates using the Internet Protocol address. DNS translates the domain name into an IP address, so the browser can load the internet resource.
You type "google.com" in your browser and it loads. But how does your computer know where Google actually is?
How does DNS work?
The DNS resolution process converts a hostname into a computer-friendly IP address. An IP address is give to each device on the is used to find the appropriate internet device, like a street address, between what a user types into their web browser and the machine-friendly address necessary to locate the example.com webpage.
To understand the process of DNS resolution, it’s important to learn about the different hardware components a DNS query must pass through. For the web browser, the DNS lookup occurs “behind the scenes” and requires no interaction from the user’s computer apart from the request
What Are DNS Records?
DNS records answer one question: "Where should this request go?"
Different record types give different answers:
"Here's the IP address" (A Record)
"Go ask that other domain" (CNAME Record)
"Send email here" (MX Record)
"These servers control this domain" (NS Record)
1. A Record: The Basic Address
What it does: Maps a domain name to an IP address.
Example:
example.com → 192.168.1.1
When someone types "example.com", DNS says "go to 192.168.1.1"
Real use: You point your domain to your server's IP address.
Key point: A records work with IPv4 addresses (like 192.168.1.1).
2. CNAME Record: The Alias
What it does: Points one domain name to another domain name.
Example:
www.example.com → example.com
blog.example.com → example.com
Real use:
Make www.yoursite.com and yoursite.com go to the same place
Use blog.yoursite.com but host on Medium
Route traffic through a CDN
Key point: CNAME redirects to another domain, which then has an A record pointing to the IP.
A Record vs CNAME
A Record: Points directly to an IP
example.com → 192.168.1.1
CNAME: Points to another domain
www.example.com → example.com → 192.168.1.1
Important: You can't use CNAME for your root domain (example.com). Only subdomains can be CNAMEs.
3. MX Record: Email Routing
What it does: Tells email servers where to send emails for your domain.
Example:
example.com → mail.example.com (priority: 10)
example.com → backup-mail.example.com (priority: 20)
How it works:
Someone emails you@example.com
Their email server checks MX records
Email goes to the server with lowest priority number
Real use: Point your domain's email to Gmail or Outlook servers.
Key point: Lower priority number = tried first. If it fails, tries the next one.
4. NS Record: Who's in Control
What it does: Says which DNS servers control your domain.
Example:
example.com → ns1.cloudflare.com
example.com → ns2.cloudflare.com
Real use: You buy a domain from GoDaddy but use Cloudflare for DNS. You change NS records to Cloudflare's servers.
Key point: NS records determine who manages all your other DNS records.
NS vs MX: The Difference
NS Record: Which servers control ALL DNS for this domain
MX Record: Which servers handle EMAIL only
How They Work Together
Real example for company.com:
A Record:
company.com → 93.184.216.34
CNAME Records:
www.company.com → company.com
blog.company.com → company.com
MX Records:
company.com → smtp.google.com (priority: 10)
NS Records:
company.com → ns1.cloudflare.com
What this means:
Main site is at that IP
www and blog point to the same server
Emails go to Google
Cloudflare manages the DNS
Complete Flow for www.company.com
Browser asks: "What's www.company.com?"
DNS checks NS records: "Ask Cloudflare"
Cloudflare checks CNAME: "It's an alias for company.com"
Cloudflare checks A record: "That's 93.184.216.34"
Browser connects to that IP
Happens in milliseconds!
Common Setups
Simple Website:
yoursite.com → 192.168.1.1 (A)
www.yoursite.com → yoursite.com (CNAME)
Website + Email:
yoursite.com → 192.168.1.1 (A)
www.yoursite.com → yoursite.com (CNAME)
yoursite.com → mail.google.com (MX)
Using CDN:
yoursite.com → 192.168.1.1 (A)
www.yoursite.com → yoursite.cdn.com (CNAME)
yoursite.com → ns1.cloudflare.com (NS)
Why Developers Need This
You'll use DNS records for:
Deploying sites: Point domain to server IP
Subdomains: Create api.yoursite.com or dev.yoursite.com
Email setup: Configure business email
CDNs: Route through Cloudflare or AWS
Debugging: Check DNS when sites don't load
Interview tip: Know A vs CNAME and what MX/NS records do.
Quick Summary
A Record: Domain → IP address
CNAME Record: Domain → Another domain (alias)
MX Record: Where emails go (with priority)
NS Record: Which servers control DNS
Remember:
A points to IPs, CNAME points to domains
MX is for email, NS is for DNS control
Lower MX priority number = higher priority
Can't use CNAME on root domain
Understanding DNS helps you deploy sites, fix issues, and ace interviews.
