Domain Name System (DNS)

The Domain Name System (DNS) is a fundamental component of the internet's infrastructure that functions as a decentralized, hierarchical "phonebook" for the internet. Its primary role is to translate human-friendly domain names, such as `www.example.com`, into the numerical Internet Protocol (IP) addresses, like `93.184.216.34`, that computers require to locate and communicate with each other over a network. This critical translation service eliminates the need for users to memorize complex IP addresses, thereby enabling intuitive navigation and access to websites, email servers, and other online resources, making it an essential protocol for modern computer networking.

1. Introduction to DNS
   1. Definition and Purpose
   2. Core Functions
      1. Domain Name to IP Address Translation
      2. Reverse DNS Lookups
      3. Service Discovery
   3. Internet Infrastructure Role
      1. Web Browsing Enablement
      2. Email Delivery Support
      3. Application Service Support
      4. User Experience Impact
   4. Historical Development
      1. Pre-DNS Era
         1. HOSTS.TXT File System
         2. Centralized Management Limitations
         3. Scalability Problems
      2. DNS Creation
         1. ARPANET Requirements
         2. Paul Mockapetris and RFC Development
         3. Initial RFC Standards
      3. Evolution and Growth
         1. Internet Expansion Impact
         2. Modern RFC Updates
         3. Internationalization Support
   5. Fundamental Terminology
      1. Domain Name
      2. IP Address
      3. Fully Qualified Domain Name
      4. Hostname
      5. Label
      6. Zone
      7. Resolver
      8. Authoritative Server
      9. Recursive Server
      10. Root Server