CoreDNS DNS Server

CoreDNS is a free and open-source DNS server written in Go that is fast, flexible, and designed for cloud-native environments. Originally created by Miek Gieben in 2016 as a successor to SkyDNS, CoreDNS became a CNCF (Cloud Native Computing Foundation) graduated project in 2019 and is the default DNS server in Kubernetes, serving DNS for millions of Kubernetes clusters worldwide. Key features: plugin architecture: CoreDNS is built around a flexible plugin chain where each plugin handles a specific aspect of DNS processing. Over 50 built-in plugins cover forwarding (forward), caching (cache), load balancing (loadbalance), rewriting (rewrite), health checks (health), metrics (prometheus), logging (log), TLS (tls), and more. Users can chain plugins in any order, and third-party plugins can be compiled in. Corefile: configuration is done via a simple Corefile syntax, where each server block defines a zone, port, and plugin chain. Zone management: serves authoritative DNS for zones (file plugin with RFC 1035 zone files, auto plugin for automatic zone discovery, etcd plugin for DNS discovery via etcd). Forwarding: forward queries to upstream resolvers (recursive resolvers like 8.8.8.8 or authoritative servers) with support for TCP and UDP, DNS-over-TLS (DoT), DNS-over-HTTPS (DoH), and DNS-over-QUIC (DoQ). Protocol support: DNS, DNSSEC validation and signing, mDNS, and gRPC-based DNS. Kubernetes integration: the kubernetes plugin provides service discovery for Kubernetes clusters. Performance: written in Go with high concurrency, handling over 100,000 queries per second per core. Prometheus metrics for monitoring. API: on-the-fly configuration reload via the reload plugin. Cross-platform: Linux, macOS, Windows, Docker. Apache-2.0.