The Domain Name System or DNS is a hierarchical naming system that deals with the administration of the domain name space (Domain Name Space). Its primary job is to resolve naming requests. This function could be explained by a comparison with a telephone information service that has current contact information and provides it when someone requests it. To do this, the domain name system uses a global network of DNS servers, which subdivide the namespace into independently managed zones. This allows decentralized management of domain information.
Every time a user registers a domain, a WHOIS entry is created in the corresponding registry and this is stored in the DNS as a “resource record”. The database of a DNS server thus becomes the compilation of all the records in the zone of the domain namespace that it manages.
The creation of the domain name system in 1983 replaced the earlier resolution procedure, which was highly error-prone and based on a local hosts file. This hosts.txt file can still be found today on UNIX-based systems in the etc/ directory and, on Windows computers, in %SystemRoot%\system32\drivers\etc.
The hosts.txt file required manual maintenance and regular updating, an effort that, as the Internet grew exponentially, was no longer possible. Today, this file is used exclusively for IP address classification in local networks. It also allows blocking web servers by automatically redirecting their address to local hosting (local host).
