Lecture on DNS

Key Concepts

• DNS: Domain Name System, often described as the internet's phone book.
  • Translates human-friendly domain names to IP addresses that computers understand.
  • Essential for accessing websites via domain names (e.g., amazon.com).

How DNS Works

• Translation Process:
  • When a user types a website address, the DNS translates this to an IP address.
  • The user's computer communicates using IP addresses, not domain names.
• DNS as a Discovery Service:
  • Helps systems find each other on the internet.
  • Stores domain name to IP address mappings in a distributed database.

DNS Process Overview

• Client Process:
  • User's device (DNS client) requests the IP address of a domain from a DNS resolver.
• DNS Resolver:
  • A server that helps find the IP address for a domain name.
  • Utilizes root hint files to begin the lookup process.
• DNS Lookup Steps:
  1. Client contacts DNS resolver to find IP address for domain.
  2. Resolver uses root hint file to find root server.
  3. Root server directs resolver to top-level domain (TLD) server.
  4. TLD server directs resolver to authoritative name server.
  5. Authoritative name server provides the IP address.
  6. Resolver returns IP address to client device.

DNS Components

• DNS Client: The device requesting domain information.
• DNS Resolver: Often hosted by an ISP, performs query processes.
• Zone File: Contains DNS records for domain names.
• Name Server: Hosts zone files and responds to DNS queries.

Importance of DNS

• Scalability and Availability:
  • DNS is distributed and hierarchical, crucial for internet stability.
  • High availability setups prevent outages by maintaining DNS records across multiple servers.

DNS in AWS

• Route 53:
  • AWS service for DNS management and domain registration.
  • Supports domain registration and hosted zones (managing name servers).
  • Registered domains come with four name servers to ensure high availability.

DNS Routing

• Routing Policies in Route 53:
  • Allows traffic direction to different endpoints based on rules.
  • Types of routing policies include simple, weighted, latency-based, geolocation, etc.

Practical Applications

• Hosting Static Websites on AWS S3:
  • S3 can host static website content, integrated with Route 53 for domain management.
  • HTTP connection is basic unless integrated with CloudFront for HTTPS.

Key Takeaways

• DNS is essential for internet navigation, translating domain names to IPs.
• Understanding DNS processes and components is crucial for managing web services and troubleshooting.
• AWS Route 53 is a powerful tool for managing DNS within cloud infrastructure.