Websites down but the internet working? That paradox is almost always DNS. This page explains the phonebook, the two-command test that proves it, and the cache that keeps old answers alive.
Ask a room of users what DNS does and most will guess. Then one day every website 'stops opening' while WhatsApp on the same Wi-Fi works — and the guessers are stuck. Ten minutes with this page and you will be the person who runs the right test first.
☝️ The internet answers by number but fails by name — the classic signature of a DNS problem, not an internet problem.
Computers deliver data to IP addresses. Humans remember names. DNS (Domain Name System) is the translator between the two: you type google.com, DNS looks it up and returns an address like 142.250.x.x, and only then does your browser connect.
This lookup happens for every website, every app and every mail server — quietly, in milliseconds, thousands of times a day. It works so well that most people only learn DNS exists on the day it breaks.
When 'the internet is not working', run these two commands in order:
ping 8.8.8.8 — tests the raw internet connection by number, using Google's public DNS server address as a well-known targetping google.com — tests whether name lookup worksIf the first succeeds and the second fails with 'could not find host', your internet is fine and only DNS is broken. If both fail, stop blaming DNS and check the gateway and the line first — name lookup cannot work on a connection that is down anyway.
By default, DHCP points your PC at the router as the DNS server, and the router forwards questions to your internet provider's DNS. That chain works, but a slow or failing middle link makes every website feel 'slow to start' while speed tests look perfect — because the delay happens before the download begins.
Well-known public phonebooks you can set by hand: Google DNS 8.8.8.8 and Cloudflare DNS 1.1.1.1. Many technicians set these directly on a PC to test whether the provider's DNS is the problem — if sites suddenly open, the diagnosis is done.
To stay fast, Windows remembers recent lookups in a local DNS cache. The price: a wrong or old answer can stick around after the real problem is fixed. The cure is one command: ipconfig /flushdns, which empties the cache so the next lookup is fresh.
Browsers keep their own cache too, which is why a site can fail in one browser and open in another during a DNS incident. Honest diagnosis always tests with nslookup google.com in Command Prompt — it shows which server answered and what it said.
The video shows the name-to-number lookup happening live — watch it, then try nslookup on your own PC.
▶️ Watch Full VideoDNS is the phonebook of the internet. You give it a name like google.com, and it returns the IP address your computer actually connects to. Without it, you would have to memorise numbers for every website.
DNS. The connection itself is healthy — data reached the server by number. Only the name-to-number lookup failed. Check the DNS server setting, try a public DNS like 8.8.8.8 or 1.1.1.1, and run ipconfig /flushdns to clear any cached wrong answer.
The default one from your router or provider works for most people. If websites feel slow to start or some names fail to resolve, switching to a public DNS such as Google (8.8.8.8) or Cloudflare (1.1.1.1) is a safe, reversible test — it changes only who answers lookups, nothing else.