Final answer:
When setting up an internal DNS server for a local network, the client devices are configured to check the internal DNS server first before querying external DNS servers.
Step-by-step explanation:
When setting up an internal DNS server for a local network, the network technician will typically configure the client devices to check the internal DNS server first before querying external DNS servers. This is done to prioritize and optimize DNS resolution within the local network.
For example, let's say the internal DNS server has an entry for a URL like 'www.example.com' mapped to an internal IP address. When a user types in 'www.example.com' in their web browser, the client devices will first check the internal DNS server. If the URL is found in the internal DNS server's records, it will return the corresponding internal IP address. If not found, the client devices will then query external DNS servers to resolve the URL.