Inventory records and dependencies
List the subdomain’s records, including service verification, mail-related records, certificates, and any delegated child zones. Confirm with service owners which records are still needed; copying only the obvious web address can break less visible integrations.
Create the destination records before switching traffic and query that provider’s authoritative servers directly. Check record types, values, proxy or flattening behavior where applicable, and any DNSSEC or delegation requirements.
Cut over and observe
Make the parent-zone change or delegation update that directs resolvers to the new provider. Keep TTL and cache behavior in mind, and avoid removing the old zone immediately because some resolvers may continue using cached delegation information.
Compare answers from authoritative and recursive resolvers, then validate the actual services. Remove the old configuration only after the transition is confirmed and rollback is no longer needed.