How does a local DNS resolve a public domain name?

DNS server diagram:

To serve internal LAN applications, such as domains, local websites, forums, OA, and ERP systems, we usually build local DNS servers.

Set the local DNS server as the preferred DNS, and access to the local system is faster.

But how does internal DNS resolve public domain names?

We generally configure a local DNS server forwarder to resolve public domain names.

Install the DNS server component in windows, open the component-> properties, and click the forwarder

Address: http://jingyan.baidu.com/article/37bce2be1169cd1002f3a283.html

How does a local DNS resolve a public domain name?