AI EncyclopediaChips & deep techMore concepts 1
DNS (Domain Name System)
DNS(도메인 이름 시스템)
The basic system of the internet that turns a domain name, like a web address, into the IP address a computer goes to.
Overview
DNS is the basic system of the internet that turns a domain name that people can read easily, such as a website address, into the IP address a computer actually goes to. When you type a name into the address bar, this system finds the address linked to that name, and that is what makes the connection possible.
DNS was set up in the early 1980s. Before that, people shared a list file of host names and addresses by hand. As the internet grew, it changed to a hierarchical database split across many servers.
How it works
When a client asks for a name, it first checks the cache. If the answer is not there, a recursive resolver asks the root server, then the top-level domain server, then the authoritative name server, one after another. Each step points to the next place to ask, and the final answer carries the IP address and a time to live (TTL).
The result is stored and reused for as long as the TTL value in the answer, so repeated queries are fewer and things get faster. The owner of a domain can change the records on the authoritative name server to move the address or to connect a new service.
Where it is used
Operators of web services connect a domain name to a server address so that users can reach the service by an address they can easily remember. Moving to another server or spreading the load across several servers can also be done by changing DNS settings.
In security checks, people look up DNS records to see which services the domains they manage are linked to. These lookups should be done only within an authorized scope, and the lookup itself does not give you any right to access anything.
Limits and misconceptions
Because of caching, a change to a DNS answer may not take effect right away. Basic queries are not encrypted, so they can be watched or tampered with along the way. Separate encrypted methods are sometimes used to prevent this.
A common misunderstanding is that a name being registered in DNS means the service is open to everyone. Knowing an address and having permission to access it are two different things, and the real protection comes from login and access settings.
An everyday example
It works like a phone book. You look up a friend's name and a number comes out. In the same way, when a browser asks for a name, DNS tells it the matching address.
Why it matters
If you know how DNS works, you can understand the path by which a service's address gets connected. You can also see that an address being visible does not mean security is broken, and that helps you make better judgments.