What Is DNS? How Names Turn Into IP Addresses
DNS turns names like google.com into IP addresses. Here is how it works, which DNS server to use and how to fix DNS errors.
DNS (Domain Name System) is the phone book of the internet. It turns names people remember, like wifirouterzone.com, into the IP addresses computers use.
DNS is the phone book of the internet. It turns names people remember, like wifirouterzone.com, into the IP addresses computers use.
Every time you open a website or app, a DNS lookup happens first. Here is how it works and how to choose a good DNS server.
How a DNS lookup works
- You type a website name.
- Your device checks its own cache.
- If not cached, it asks the DNS server set by your router, usually the router itself.
- The router asks your ISP or a public DNS service, which finds the answer from the authoritative servers.
- The IP address comes back and your browser connects.
I picture the lookup as a phone book search, since that is the step people actually remember.
Popular DNS servers
| Provider | Addresses | Notes |
|---|---|---|
| Your ISP | Automatic | Default on most routers |
| Cloudflare | 1.1.1.1, 1.0.0.1 | Fast, privacy focused |
| 8.8.8.8, 8.8.4.4 | Very reliable | |
| Quad9 | 9.9.9.9 | Blocks malicious domains |
| Cloudflare Families | 1.1.1.3 | Blocks malware and adult sites |
Change it for every device at once: change DNS on your router.
I start with Cloudflare when someone asks me to pick one, since it is fast and easy to remember.
DNS terms you will see
- DNS cache: stored answers that speed up repeat visits.
- TTL: how long an answer can be cached.
- DNS over HTTPS (DoH): encrypted DNS used by browsers.
- Private DNS (Android): encrypted DNS for the whole phone.
I explain TTL first, since it is the term that causes the most confusion.
Common DNS problems
- DNS server not responding: see our step-by-step fix.
- Site loads on mobile data but not WiFi: a DNS cache or router DNS issue. Flush DNS or restart the router.
- Website moved and still fails: old cached records. Clear the cache.
I flush the cache before I blame the router, since a stale record is the usual cause.
Why switching DNS can feel faster
Every new website starts with a DNS lookup. If your ISP’s DNS servers are slow or overloaded, there’s a small delay before each page starts loading. Switching to a fast public DNS like Cloudflare or Google can shave those delays off.
It won’t increase your download speed, but browsing can feel snappier, especially on sites that load content from many different domains. I notice the difference most on sites that load from many places at once.
Encrypted DNS: DoH and DoT
Traditional DNS requests are sent in plain text, so your ISP or anyone on the network can see which sites you look up. Encrypted DNS hides them:
- DNS over HTTPS (DoH): built into Chrome, Firefox, Edge and Windows 11.
- DNS over TLS (DoT): used by Android’s Private DNS setting.
Both work with providers like Cloudflare (1.1.1.1) and Google (8.8.8.8). Turn it on in your browser or phone settings. I turn on DoH in the browser first, since it is the easiest place to switch it on.
DNS caching: why changes take time
To avoid looking up the same name again and again, your device, browser and router all keep a short memory of recent DNS answers. This is called caching, and each answer has a time-to-live (TTL) that says how long to keep it.
That’s why a website that moved to a new server might still load the old one for a while, or why changing DNS settings doesn’t take effect straight away. Flushing the DNS cache on your device clears it: on Windows run ipconfig /flushdns, and restarting your browser clears its cache.
I wait a little before I declare a change broken, since the old answer can linger.
Test whether DNS is your problem
- Open Command Prompt or Terminal.
- Run
nslookup google.com. If you get addresses back, DNS works. - Run
nslookup google.com 1.1.1.1to test Cloudflare directly. - If the second works and the first doesn’t, your default DNS server is the problem.
- Switch your router or device to a public DNS server.
I run the second command first, since it tells me whether my own DNS is the problem.
DNS and privacy
Every website you visit starts with a DNS lookup, which means your DNS provider can see a list of the sites you look up. With your ISP’s default DNS, that’s your ISP. Switching to a privacy-focused provider and turning on encrypted DNS (DoH or DoT) keeps those lookups away from anyone on the network and limits who can log them.
Cloudflare (1.1.1.1) and Quad9 (9.9.9.9) both publish privacy policies that limit logging. It isn’t a full privacy solution, since your ISP still sees which IPs you connect to, but it closes one of the easiest leaks.
I pair a private DNS with encrypted DNS, since one without the other leaves a gap.
