Final answer:
The type of DNS query when the DNS server sends the request to the Root Servers is called an iterative query, where the DNS server iteratively queries different servers to find the authoritative DNS server for the requested domain name.
Step-by-step explanation:
The type of DNS query when the DNS server sends the request to the Root Servers is called an iterative query.
In an iterative query, the DNS server sends a request to the Root Servers, and the Root Servers respond with a referral to the Top-Level Domain (TLD) servers. The DNS server then sends another query to the TLD servers to obtain information about the authoritative DNS server for the requested domain name. This process continues until the authoritative DNS server is found, and the DNS server obtains the IP address for the requested domain.
For example, if a user wants to access 'www.example.com', the DNS server starts with a query to the Root Servers, then queries the TLD servers for the 'com' domain, and finally queries the authoritative DNS server for 'example.com' to obtain the IP address.