After migrating to Cloud DNS, the final step of verifying changes by authoritative lookup is crucial because it ensures that the DNS records have been correctly set up and are propagating as expected. Authoritative DNS lookups confirm that the new DNS settings are functioning properly, allowing you to check whether the domain name resolves to the correct IP address as configured in Cloud DNS.
This verification process is essential to ensure that the site or service can be reached successfully after migration. If the authoritative lookups show the expected DNS records, it indicates that the migration was successful, and users will be directed to the proper resources.
The other options, while relevant to different stages or aspects of DNS management, do not represent the final step post-migration. Updating DNS keys pertains to securing zone transfers and authentication but isn’t necessary after initial migration verification. Checking internal DNS resolution typically follows creating or modifying DNS entries but isn’t the definitive end step. Lastly, reconfiguring Cloud SQL settings is unrelated to the DNS migration process itself.