System architecture

The Private DNS system consists of the control layer and the resolution layer.

Control layer: The control layer provides services by using the console and API operations. Located in the China (Zhangjiakou) and China (Hangzhou) regions, the control layer lets you add, delete, modify, query, and save Domain Name System (DNS) resolution data, configuration data, and log data.
Resolution layer: The resolution layer provides services by using DNS server clusters around the world. Located in all Alibaba Cloud regions and zones, the resolution layer receives the DNS records allocated from the control layer, and responds to the DNS requests for the DNS records.

Control layer: The control layer is deployed in the China (Zhangjiakou) and China (Hangzhou) regions. Control server clusters are deployed in multiple zones and load balancing is achieved among the control servers in each cluster. The system employs a dual-region and multi-zone architecture where control server clusters in a zone can handle all DNS requests forwarded to other zones in the same region, ensuring high availability.
Resolution layer: The resolution layer is deployed around the world. A DNS server cluster is deployed in each zone and load balancing is achieved among the DNS servers in each cluster. A DNS request is forwarded to the nearest zone. If the DNS server cluster in the zone is unavailable, the DNS request is sent to the DNS server cluster in a nearby zone within the same region. The DNS server cluster in a zone can handle all DNS requests forwarded to other zones in the same region. Disaster recovery cannot be achieved among DNS server clusters deployed in different regions.