DNS (Domain Name System) is essentially the internet's phone book. When you type a website name like "google.com" into your browser, your computer doesn't actually know how to find that site by name — it needs a numeric address (an IP address, something like 142.250.80.46) to actually connect. DNS is the system that translates the name you typed into the numeric address your computer needs.
The actual process, simplified
- You type a website address into your browser
- Your computer asks a DNS server (usually provided automatically by your ISP, or one you've configured manually) "what's the IP address for this name?"
- The DNS server responds with the correct numeric address
- Your computer then connects to that actual address to load the website
This entire process typically happens in a fraction of a second, invisibly, every single time you visit any website.
Why DNS caching exists
To avoid repeating this lookup process every single time, your computer remembers ("caches") recent DNS lookups for a while. This makes browsing faster, since it doesn't need to ask "what's the address for google.com?" again every time you visit — it already knows from a few minutes ago.
Why this causes problems sometimes
The cache can become outdated or "stuck" — if a website's actual IP address changes (which does happen, particularly for businesses changing hosting providers) but your computer is still using an old cached answer, you'll fail to connect even though the site is genuinely up and working for everyone else. This is exactly why "flush your DNS cache" is such a common troubleshooting step — it forces your computer to ask fresh, rather than relying on a potentially outdated cached answer.
How to flush your DNS cache
- Press Windows key, type
cmd, right-click Command Prompt → Run as administrator - Type
ipconfig /flushdnsand press Enter - You should see a confirmation message that the cache was successfully flushed
Why you can change your DNS server
By default, your computer uses whatever DNS server your ISP provides automatically. You can manually switch to a different, public DNS provider instead — common choices are Google (8.8.8.8 / 8.8.4.4) or Cloudflare (1.1.1.1 / 1.0.0.1). People do this for a few reasons: some public DNS providers are faster or more reliable than a particular ISP's default servers, and some offer additional features like basic content filtering or improved privacy practices.
To change it: Settings → Network & internet → [your connection] → DNS server assignment → Edit, switch to Manual, enable IPv4, and enter your preferred DNS addresses.
The bottom line for troubleshooting
If a specific website won't load while others work fine, or a site that used to work suddenly doesn't, DNS is a genuinely common and easy-to-rule-out cause — flushing your cache and/or trying a different DNS server are both quick, low-risk steps worth trying before assuming something more serious is wrong.