ExternalDNS is a third-party, open-source tool designed to automate the management of DNS records for Kubernetes clusters. It integrates seamlessly with Kubernetes to dynamically update DNS records in response to changes in your cluster, enabling smooth automation of exposed services, APIs, and applications. Originally developed to support AWS Route53 and Google CloudDNS, it has since expanded to support a wide array of DNS providers, making it a versatile option for cloud-native environments.