I’ve always used 8.8.8.8 or 1.1.1.1, but I realized I didn't actually understand how the resolution chain worked under the hood. To fix that, I built a DNS resolver in Go that performs true iterative resolution from the root servers down, with no upstream dependencies.

Unlike a simple DNS forwarder, this server doesn't just "ask someone else." It implements the full hierarchy: Root → TLD → Authoritative → Final Answer.

Key Technical Challenges I tackled:

Iterative Navigation: Setting RecursionDesired = false so that upstream servers treat the project as a peer resolver.

The "Glue Record" Problem: Implementing sub-resolution where the resolver has to pause the main query to resolve a nameserver's hostname before it can continue.

TTL-Aware Concurrency: Using sync.Map for a thread-safe cache that automatically respects record expiration.

State Management: Handling referrals and avoiding infinite loops in heavily nested zones.

Architecture: The server is built using raw UDP sockets and the dnsmessage package for packet parsing. It handles thousands of concurrent requests using Go’s concurrency primitives.

UDP Listener: Standard net.PacketConn loop.

Resolver Engine: Recursive logic that walks the hierarchy starting from A.ROOT-SERVERS.NET.

Local Overrides: A JSON-based configuration for authoritative local records (useful for dev environments or ad-blocking).

I’d love to hear from anyone who has worked on DNSSEC or handled high-traffic DNS infrastructure. What are the common pitfalls when moving from a "toy" resolver to a production-grade one?

Source Code: https://github.com/Jyotishmoy12/go-dns-server