Managing DNS records in large Kubernetes environments is complex, but tools like ExternalDNS streamline this process by automating DNS record synchronization with Kubernetes resources, enhancing scalability and reducing manual errors. ExternalDNS works with major DNS providers and, when integrated with cert-manager, also automates TLS certificate management, creating a comprehensive automation framework. Despite its benefits, scaling ExternalDNS can pose challenges such as performance bottlenecks, API rate limits, configuration complexities, and security risks, which can be mitigated through strategies like selective resource syncing, rate limit management, standardized configurations via Helm charts, and stringent security measures. Combining ExternalDNS with cert-manager further simplifies DNS and TLS management by creating a seamless workflow for domain validation and certificate issuance, especially useful for wildcard certificates. By addressing these challenges and integrating best practices, administrators can confidently scale DNS and TLS automation, ensuring secure and efficient deployments within Kubernetes clusters.