ExternalDNS synchronizes Kubernetes ingresses and services with external DNS providers, filling a hole previously filled by kops dns-controller, Zalando's Mate or route53-kubernetes — the last two of which have been deprecated in favor of ExternalDNS. The tool makes internal Kubernetes resources discoverable via public DNS servers, removing a sometimes manual step to update DNS records when an ingress host or service's IP address changes. It supports a huge list of DNS service providers out of the box with more being added via community support. As the old joke goes, it's always DNS.