CoreDNS is a DNS server that provides name resolution and service discovery for microservice-based applications, particularly within Kubernetes clusters. It is customizable, allowing adjustments beyond simple DNS lookups, and can now be monitored using Datadog's new integration, which provides insights into CoreDNS metrics to better understand Kubernetes cluster activities. Key metrics include request rates, DNS latency, error codes, and resource usage, all of which help in identifying performance issues and optimizing configurations. Users can also monitor how CoreDNS handles cache requests, forwards them to upstream DNS servers, and responds to errors. Custom plugins can be integrated to extend CoreDNS functionality, and their metrics can be tracked in Datadog dashboards for a comprehensive view of DNS activity. To start monitoring, users need to enable the Prometheus plugin, allowing metric collection and integration into Datadog for enhanced performance visibility across Kubernetes environments.