History of DNS
The Domain Name System (DNS) originated in the early 1980s as a decentralized, hierarchical system to map human-readable domain names (ex: www.microsoft.com) into numerical IP addresses (ex: 23.214.125.208). This lookup service simplified internet navigation for humans because they were easier to remember, brand able and allowed ip records (server addresses) to be updated without disruption to the user.
DNS was developed to replace the manually maintained host tables (hosts file). As more computers adopted the IP standard and joined the network, manually maintaining host tables became unmanageable for administrators.
DNS is organized in a tree-like structure of administrative zones of control. Each zone responds to resource location requests. The administration of domain and sub domain name can within a zone, can be delegated beginning at the root zone. A zone can contain as many domains and sub domains as the administrator chooses. Each sub domain is separated by a dot.
a practical example or way of looking as zones and records is to picture, or define, a city or neighbourhood. In a city, which is analogous to a zone, you have many different service or resources such as electricity and transit. The DNS hierarchy would be the city name, dot, resources name. If that resource, also had sub resource, then the pattern would repeat. City name, dot, resource name, dot, sub resources name, dot sub resource name, etc.
When a resource is requested, the DNS service reads the request from right to left asking each name server along the path for the resource record associated with that name, like following a map. First, the root zone is queried and pointed to the nameserver in control of the toronto zone. The toronto name server then takes over the job or looking up and returning either the resource or the authorized nameserver in control of the sub zone. The same process the root zone performed e when delegating the resource request to the toronto zone. The sub zone can control all zones below it, or delegate part of that zone to another nameserver.
writting out the DNS hierachy, we start from right to left. The leading dot is generally omitted, but left in here to show the full syntax.: printer.office.toronto.
Constantly being redirected to servers and services listed in the service records until it gets a satisfactory response.
A service could The first DNS implementation occurred in 1984, enabling users to access websites and services using human-readable names rather than complex IP addresses. This created one of the first distributed database across interconnected servers and DNS rapidly became a foundational internet protocol, evolving to support various record types and security extensions like DNSSEC. Its vital role persists today.
Key Lesson Concepts:
- The DNS system translates domain names into IP addresses.
- The Early internet used host tables for name-to-address mappings.
- DNS version 1 introduced a single "hosts.txt" file.
- DNS version 2 introduced decentralized name servers.
- DNS version 3 improved performance with caching and added support for multiple record types.
- DNS plays a vital role in the internet with millions of domain names being resolved daily.
An example of a HOST.txt file. In this example, when a user attempted to connect to server "hostname1," the system references its local hosts.txt file to find the corresponding IP address (192.168.1.1).
192.168.1.1 hostname1
192.168.1.2 hostname2