The DNS system in a computer translates domain names into IP addresses. Think of it as the phone book on a computer. You can enter the phone number of anyone in the book and get the name’s IP address. A DNS server then translates requests for specific domains to IP addresses and controls which servers can access those domains. The process is called DNS resolution. Here’s a basic overview of the DNS system in a computer.
The DNS works in a hierarchy of servers that answer queries from within and outside of a domain. Each server gives authoritative answers and forwards requests to the next server. These servers are managed by the ISP. DNS names are contained within URLs and are made up of multiple label parts. They are read from right to left and each label denotes a subdivision of the domain. DNS servers maintain a directory of all hosts that are available on the internet.
The DNS works in the same way as a phone book, mapping alphabetic names to numerical IP addresses. Just as the phone book maps names to numbers, the DNS maps domain names to IP addresses. When you visit a web page, a DNS query is made and the computer learns the IP address associated with it. This process helps users and computers navigate the web easily. In fact, the DNS system has become an essential part of the Internet since 1985.
When a DNS query is made, a recursive DNS server sends a query to an authoritative name server (ANS). This server contains DNS resource records and is the final checkpoint. If it doesn’t have the answer, the DNS recursor then asks for that information again until it reaches an authoritative DNS server. At the end of the DNS query, a DNS server returns the IP address of the requested hostname.
DNS queries can be iterative, recursive, or non-recursive. In the former, the DNS client requests multiple DNS servers until the query is satisfied. A DNS server may respond with an answer or error message if the requested resource is already stored in its cache. A DNS client may also respond with a request to an authoritative DNS server. In the latter case, a DNS resolver will use the resource in its cache.