DNS (Domain Name System) name resolution is the process by which domain names are translated into IP addresses, allowing devices to communicate with each other over the internet. DNS name resolution is necessary because domain names, such as www.example.com, are easier for humans to remember and use than IP addresses, such as 192.0.2.1, which are used by computers to identify each other on the internet.
When a device wants to communicate with another device using a domain name, it sends a DNS query to a DNS server. The DNS server responds with the IP address associated with that domain name, allowing the device to establish a connection. There are two types of DNS queries that a device can send to a DNS server: iterative and recursive.
Iterative DNS queries are simple and straightforward. When a device sends an iterative DNS query to a DNS server, the server responds with either the IP address associated with the requested domain name or an error message if the domain name is not found. If the DNS server does not have the IP address associated with the requested domain name, it returns a referral to another DNS server that may have the answer. The device then sends another iterative query to the referred DNS server, and the process continues until the IP address is found or an error message is returned.
Recursive DNS queries are more complex and involve more steps. When a device sends a recursive DNS query to a DNS server, the server not only responds with the IP address associated with the requested domain name, but it also searches for the answer on behalf of the device. If the DNS server does not have the IP address associated with the requested domain name, it sends a query to another DNS server, and the process continues until the IP address is found or an error message is returned. Once the DNS server has found the IP address, it responds to the original device with the answer and caches the answer so that it can quickly respond to future queries for the same domain name.
Iterative DNS queries are simpler and faster but require the device to do most of the work of finding the IP address associated with a domain name. Recursive DNS queries are more complex and slower but allow the DNS server to find the IP address on behalf of the device and cache the answer for future use.
