DNS - Eli5Dev

What is DNS?

The Domain Name System (DNS) is the internet’s phonebook. It’s a system that translates human-readable domain names (like www.example.com) into machine-readable IP addresses (like 192.0.2.1) that computers use to identify each other on the network.

DNS is essential because while domain names are easy for people to remember, computers access websites based on IP addresses.

Simple Analogy

Think of DNS like a postal service’s address lookup system:

Domain Names vs. IP Addresses:
Like the difference between saying “The White House, Washington D.C.” (domain name) versus “1600 Pennsylvania Avenue NW, Washington, D.C. 20500” (IP address). The first is memorable and human-friendly, while the second is precise but harder to remember.

They might be the same physical location, but we have to present the information in a certain way, optimized for the reader.

How DNS Works

You type “google.com” in your browser
Your computer checks if it already knows the IP address (like checking your recent calls)
If not, it asks a DNS resolver (like asking the operator)
The resolver might know, or it might ask other DNS servers (like the operator checking different phone books)
Eventually, it finds the correct IP address and tells your computer
Your computer connects to that IP address
Your computer remembers (caches) this information for a while

Key Concepts

Domain Name: The human-readable address (like example.com)
IP Address: The machine-readable numerical address (like 192.0.2.1)
DNS Resolution: The process of converting a domain name to an IP address
DNS Records: Different types of information stored in the DNS:
- A Record: Maps a domain name to an IPv4 address
- AAAA Record: Maps a domain name to an IPv6 address
- CNAME Record: Creates an alias from one domain to another
- MX Record: Specifies mail servers for the domain
DNS Caching: Temporarily storing DNS lookups to improve performance
TTL (Time To Live): How long a DNS record should be cached before requesting fresh information