DNS server definition
A DNS server is a computer system that translates domain names (like www.example.com) into IP addresses (like 192.0.2.1). When a user enters a domain name into their browser, the browser sends a request to a DNS server, asking to give an IP address that can be used to connect to the web server hosting the website.
DNS servers use a hierarchical system to store and distribute domain name information. At the top of the hierarchy are the root DNS servers, which maintain information about the top-level domains (like .com, .org, and .net). Below the root servers are the authoritative DNS servers for each domain that maintain information about the IP addresses associated with the domain’s web servers.
Recursive DNS servers
A recursive DNS server is responsible for resolving domain names by communicating with other DNS servers on behalf of the client. When a client requests a domain name resolution, the recursive server will query other DNS servers until it finds the IP address associated with the domain name. The recursive server then caches this information so that it can respond quickly to future requests for the same domain name.
Authoritative DNS servers
An authoritative DNS server is responsible for actually providing the IP address associated with a particular domain name. When a recursive server sends a query, the authoritative server provides a direct answer rather than referring the query to another server.