The Domain Name System (DNS) is a computer protocol that manages domain names and their associated DNS zones. Its most basic component is a database of names and addresses stored in special servers called dns servers. These servers maintain authoritative copies of zone records. Some DNS servers are dedicated to name resolution, while others simply forward requests and cache responses. Each DNS zone is assigned a set of authoritative name servers, which are stored in the parent domain zone.
The DNS directory is distributed across many domain servers, resulting in more than a quarter trillion domain names worldwide. Unlike the Internet, DNS is not stored on a single mega server, but on a hierarchy of name servers that communicate constantly. Domain names are often linked to multiple IP addresses, and some websites have dozens of IP addresses. DNS enables these web sites to function properly. By using DNS, websites can easily identify which IP address is associated with their domain names.
Caching DNS records reduces DNS query response time by storing answers locally, so they are ready when clients make a DNS request. By default, most browsers cache DNS data. When a user makes a DNS request, the browser checks its cache first, before requesting the name server in question. This saves network resources and time. DNS caches are essential for optimizing the performance of websites and other applications. To get the most out of these caches, use Chrome or Firefox.
The DNS resolver is built into the operating system and can be accessed through a software library. It addresses DNS queries with the functions “gethostbyname” and “gethostbyaddr” (gethostbyname) and returns the IP address and main domain name associated with the domain name. To use DNS resolver, you must know the IP address of one or two DNS servers: the primary DNS server and the secondary DNS server. It is important to note that the DNS resolver in the operating system caches the answers to DNS queries.
The domain name system defines several types of requests for communicating with other DNS nodes. The first type of request is an HTTP POST, while the second type is a GET. Those are the two most common types of requests, which are the most common. RFC 2671 outlines the protocol and defines its request types. In addition, EDNS specifies additional protocol elements and overhead that can improve DNS response time. However, DNS doesn’t support HTTP POST, but it can still be used to transfer information.
Another type of DNS query is a recursive query. Recursive queries refer to multiple nameservers. When an application makes a query to a domain name, it requests the IP address associated with it. A recursive query, on the other hand, refers to several nameservers and sends the query to the next nameserver. Eventually, the DNS server responds to the query. It also stores information about the query.
