The Domain Name System (DNS) is like the internet’s phone book. It translates human-readable domain names (e.g., www.example.com) into machine-readable IP addresses (e.g., 192.0.2.1), allowing you to access websites easily.

How DNS Works

1. User Request

• You type a website URL (e.g., www.example.com) into your browser.

2. DNS Query

• Your computer sends a DNS query to a DNS resolver (usually provided by your internet service provider).

3. DNS Resolver Checks Cache

• The resolver may already know the IP address and respond quickly, or it may need to ask other DNS servers.

4. Root DNS Servers

• If needed, the resolver asks the root DNS servers where to find information about the domain.

5. TLD DNS Servers

• The root server directs the resolver to the Top-Level Domain (TLD) servers (e.g., .com, .org).

6. Authoritative DNS Servers

• The resolver finally asks the authoritative DNS server for the domain, which holds the correct IP address.

7. Connection

• Your device receives the IP address and uses it to connect to the website server.

Common DNS Records

• A Record: Links a domain to an IPv4 address (e.g., www.example.com -> 192.0.2.1).
• MX Record: Directs email to mail servers for the domain.
• CNAME Record: Points a domain to another domain (e.g., blog.example.com -> example.com).
• NS Record: Specifies which DNS servers handle the domain.
• TXT Record: Stores text info like email verification (e.g., SPF, DKIM).

DNS Caching

• Local Cache: Your computer remembers DNS info to speed up future requests.
• ISP Cache: Your internet service provider might store DNS info for faster access.
• Authoritative Cache: The authoritative server stores DNS info for a set period.

DNS Propagation

When DNS records are updated, changes take time to spread across the internet. This can take from a few minutes to 48 hours.

Conclusion

DNS helps convert website names into IP addresses, making it possible to access websites easily.