What is DNS and what does it actually do?
DNS (Domain Name System) is the internet's phone book: it translates easy-to-remember domain names into the numeric IP addresses computers actually use to communicate. Every time you enter an address in a browser, a DNS lookup happens first, before the connection to the server is made.
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What exactly does DNS do?
When you type a domain such as ipnow.kr into a browser, your device first asks a DNS server what IP address corresponds to that name. Only after the DNS server answers does the actual connection to that IP happen.
Without domain names, people would have to memorize numeric addresses such as 203.0.113.10 for every website. DNS means you only need to remember the name.
In what order does a DNS lookup happen?
A device first checks its own cache for an answer, and if it is not there, asks the configured DNS server, usually one your ISP assigned automatically. If that server does not know either, it recursively asks other DNS servers.
Once a lookup succeeds, the result is cached for a while, so revisiting the same site later can skip the lookup and connect right away.
How do I check which DNS server I am currently using?
Most people never set this manually — the ISP automatically hands out a DNS server to the router or device. On Windows, run ipconfig /all; on Mac or Linux, check network settings or run scutil --dns or resolvectl status.
How to switch to a DNS server of your choice on each device is covered in how to change your DNS server.
How does public DNS differ from your ISP's DNS?
Public DNS services such as Cloudflare (1.1.1.1) or Google (8.8.8.8) are not tied to any single provider and can be used by anyone. Your ISP's DNS is the server your provider automatically assigns to the line you subscribed to.
Speed, reliability and content filtering policies can differ by both provider and service, so it is hard to say one is always better than the other.
Frequently asked questions
Does changing DNS make my internet faster?
Response times can improve in some cases, but the actual difference depends on your ISP's line condition and the sites you visit, so it is not guaranteed to be faster.
What is a DNS cache?
It is a temporary local record of a domain-to-IP lookup, kept by your device or browser. It lets you skip the DNS lookup and connect faster the next time you visit the same site.
How do I check my DNS server address?
On Windows use ipconfig /all in Command Prompt; on Mac check network details in System Settings; on Linux try a command such as resolvectl status.
Is DNS the same thing as an IP address?
No. An IP address is the numeric address actually used for communication, while DNS is the system that connects that number to an easy-to-remember domain name. See what is my IP address for more on IP addresses themselves.