Module 3
Module 3: DNS for Developers — Optimizing Applications and Infrastructure
⏱ ~6 hours
Move beyond getaddrinfo(). Learn how DNS shapes application performance, service discovery, and security in production systems — with real code.
Module 3: DNS for Developers
You call getaddrinfo() or let your HTTP client handle it. An IP comes back. You move on.
But DNS is doing a lot more than returning IPs. It's shaping your latency, your failover behavior, your service discovery, your TLS security, and your Kubernetes pod startup time. Most of that happens invisibly, until it breaks.
This module is for backend engineers who are ready to stop treating DNS as infrastructure someone else manages, and start treating it as a tool they can actually control.
What You'll Learn
- How DNS resolution actually works at the library level, and where it hides latency
- How to use SRV records for real service discovery instead of hardcoded host:port pairs
- DNS-based load balancing: where it works, where it fails, and why clients lie to you
- DANE: how to cryptographically bind TLS certificates to DNS records
- Docker and Kubernetes DNS: the 127.0.0.11 you didn't know existed, and the ndots:5 problem that slows every pod
- Split-horizon DNS in AWS, GCP, and Azure private zones
- Performance techniques that can cut DNS latency by 80% with five lines of code
- A complete hands-on project: a working DNS-aware service discovery system in Go and Python
Prerequisites
Module 1 (DNS Fundamentals) and Module 2 (DNS Security). You should understand how recursive resolution works, what TTLs mean, and what DNSSEC does. If you're fuzzy on any of those, revisit before continuing.
Who This Is For
Backend engineers. SREs. Platform engineers. Anyone who writes services that talk to other services over a network. If you've ever added retry(3) to a DNS call hoping it would fix the timeout, this module is for you.
Lessons
| # | Title | Focus |
|---|---|---|
| 01 | DNS Programming Interfaces and Libraries | getaddrinfo, dnspython, miekg/dns, async vs blocking |
| 02 | Integrating DNS into Application Architecture | SRV records, service discovery, DNS as config |
| 03 | DNS-Based Load Balancing and Traffic Management | Round-robin, geo-DNS, Route 53, failover |
| 04 | Implementing DANE for Enhanced Security | TLSA records, DNSSEC dependency, email use case |
| 05 | DNS in Microservices and Container Environments | Docker DNS, CoreDNS, ndots:5, kubectl debugging |
| 06 | DNS and Service Discovery in Cloud Environments | Route 53 private zones, Consul, split-horizon |
| 07 | Performance Optimization Techniques | Prefetching, TTL tuning, in-process caching, benchmarking |
| 08 | Hands-on: Building DNS-Aware Applications | Full working code in Go and Python |
Let's start with the interface every application uses without thinking — and learn why that's a problem.