IP Addresses & DNS
How computers identify each other using unique IP addresses and how DNS maps human-friendly names to those addresses
Overview
IP addresses and DNS (Domain Name System) are fundamental to how computers communicate on the internet. IP addresses are unique numerical identifiers for devices, while DNS translates human-readable domain names into IP addresses.
Think of DNS as the internet's phone book - instead of remembering complex numbers, we use memorable names that get translated to the actual addresses.
Key Concepts
IP Address
A unique numerical label assigned to each device on a network. IPv4 uses 32-bit addresses (e.g., 192.168.1.1), while IPv6 uses 128-bit addresses.
DNS (Domain Name System)
A hierarchical distributed database that translates human-readable domain names (like google.com) into IP addresses.
DNS Resolution
The process of converting a domain name to an IP address through a series of DNS server queries.
How It Works
DNS Resolution Process:
- You type "www.example.com" in your browser
- Browser checks its cache for the IP address
- If not cached, query goes to DNS Resolver (usually your ISP)
- Resolver checks its cache, if not found, queries Root DNS servers
- Root servers direct to TLD (Top Level Domain) servers (.com, .org, etc.)
- TLD servers direct to Authoritative Name Servers for the specific domain
- Authoritative server returns the IP address
- Resolver caches the result and returns IP to your browser
- Browser connects to the server at that IP address
Use Cases
Translating website URLs to server IP addresses
Email routing (MX records)
Load balancing through DNS round-robin
CDN routing to nearest server
Service discovery in microservices
Best Practices
Set appropriate TTL values (lower for frequently changing IPs, higher for stable ones)
Use multiple DNS providers for redundancy
Implement DNSSEC for security
Monitor DNS query performance
Use CDN-friendly DNS configurations
Keep DNS records up-to-date and clean
Interview Tips
What Interviewers Look For
- •
Explain the hierarchical structure: Root → TLD → Authoritative
- •
Discuss DNS caching at multiple levels (browser, OS, ISP)
- •
Mention TTL and its impact on change propagation
- •
Talk about DNS as a potential performance bottleneck
- •
Explain how DNS can be used for load balancing and failover
- •
Discuss security concerns like DNS spoofing and how DNSSEC helps
Related Topics
- Client-Server ArchitectureThe core concept where a client (browser/mobile app) requests data and a server processes and responds
- HTTP & HTTPSThe rules for communication, including headers, cookies, and the importance of encryption via SSL/TLS in HTTPS
- APIs (REST vs. GraphQL)The structured ways clients interact with servers, comparing REST with GraphQL approaches