Technitium DNS Server is a full-featured, cross-platform DNS server written in C# (.NET). It serves both authoritative and recursive DNS with support for DNSSEC, DNS-over-TLS/HTTPS/QUIC, EDNS Client Subnet, caching, blocking, and a built-in DHCP server. The server includes a web-based management console with REST API, a Windows system tray app, and a plugin system that allows extending functionality via DNS apps (e.g., geo-location, failover, query logging to SQL databases, block pages). The architecture uses a custom domain tree data structure for efficient lookups, a zone management hierarchy (primary, secondary, stub, forwarder, catalog), and a channel-based producer-consumer pattern for logging and statistics. The codebase is actively maintained with frequent releases and security fixes. While the overall design is solid and modular, some files are large and there is reliance on binary serialization with versioning that adds complexity.