On paper, DNS is a simple request-response protocol. In reality, building an authoritative nameserver that delivers under heavy load, processes malformed packets safely, and resists DDoS attacks is a complex engineering challenge.

This talk peels back the layers of erldns, DNSimple's open-source high-performance DNS server, to explore the fundamental architecture required to handle millions of queries per second. We will focus on:

• Simplified Resolution: How a special binary tree structure drastically simplifies the DNS resolution logic, making complex requirements like empty non-terminals and handling zone cuts trivial.
• Concurrency Models: How to structure a system that isolates failures per-request so that a crash in one query never brings down the server.
• Traffic Management: Strategies for handling UDP floods and managing TCP connection pools without exhausting resources.
• Packet Handling: The nitty-gritty of parsing binary DNS wire formats safely.

While the reference implementation uses Erlang, the architectural lessons on isolation, supervision, and fault tolerance are applicable to any language. This session is designed for developers and operators who want to understand the "nuts and bolts" of how robust DNS software is built.

Project Links: - DNS Server (erldns): https://github.com/dnsimple/erldns - DNS Library (dns_erlang): https://github.com/dnsimple/dns_erlang