DNS is the phonebook that turns website names into addresses your computer can reach. Most people use their ISP's DNS by default, which usually works fine — but changing to a faster or more private alternative can sometimes improve speed or reduce tracking. The process is safe as long as you change one setting at a time and test before moving on.
What DNS does, and when you might change it
When you type "google.com" in your browser, your device asks a DNS server "what's the IP address for google.com?" That server is usually run by your ISP and is fine for most people. You might change it for speed (Cloudflare's 1.1.1.1 is often faster), privacy (same provider doesn't also bill you), or content filtering (some provide family-safe blocking). Changing DNS won't fix slow internet if your actual connection is the bottleneck — it only improves the name-to-address lookup step.
The most commonly used alternatives
Cloudflare (1.1.1.1 and 1.0.0.1) is fast and privacy-focused. Google (8.8.8.8 and 8.8.4.4) is reliable but logs lookups. Quad9 (9.9.9.9 and 149.112.112.112) blocks malware sites. OpenDNS (208.67.222.222 and 208.67.220.220) allows filtering. Pick one and write down both IP addresses — you'll need both the primary and secondary.
Where to change DNS: router vs. device
Changing DNS on your router affects all devices connected to it — simpler and less repetitive, but if the DNS fails, all your devices fall back to ISP DNS at the same time. Changing DNS on individual devices affects only those devices — more control, but more steps if you have many devices. Most people change the router first; it's the most efficient approach. If you're troubleshooting a specific device's slowness, change that device only to see if DNS is the culprit.
How to change DNS on your router
Open your router's admin page (usually 192.168.1.1 or 192.168.0.1 — check the sticker on the back) and log in with your admin password. Look for a "DNS" or "DHCP" section, usually under "Network" or "Internet" settings. You'll see "Primary DNS" and "Secondary DNS" fields. Write down the current values first. Replace them with your chosen provider's IPs (primary and secondary). Save the settings — the router will reboot, and your connection will briefly drop. After about two minutes, everything should reconnect automatically.
Test before and after
Before changing, open a command prompt or terminal and type nslookup google.com — it'll show you your current DNS server. After changing the router settings and rebooting, run the same command again. You should see the new DNS IP in the results. If you see the old IP, the change didn't stick — wait another minute and try again, or check your router's interface to confirm the settings were saved.
If websites stop working
Change DNS back to your ISP's immediately — if you wrote down the original values, just log back into the router and restore them. Then reboot the router again. If you didn't write them down, ISP DNS is usually "0.0.0.0" or similar placeholder that tells devices to use the ISP default. Some routers also have a "reset DNS to default" button. If changing DNS broke things, the most likely cause is a typo — check that you entered both numbers correctly, with no spaces or dots in the wrong places.
Changing DNS on individual devices
Windows: Settings > Network > Advanced > DNS server settings. Choose manual and enter primary and secondary IPs. Mac: System Preferences > Network > Advanced > DNS. Click the + button and add IPs one by one. iPhone/iPad: Settings > Wi-Fi > your network name > DNS. Tap Configure DNS > Manual and enter both IPs. Android: Varies by manufacturer, but usually Settings > Network > DNS (some phones default to system DNS only). If your phone doesn't let you change it, change the router DNS instead — it will cover all your devices.
How to know if it's actually helping
After a full day on the new DNS, compare your browsing speed to before — is anything actually faster? DNS lookup is usually fast enough that you won't notice, especially on a fiber or cable connection. If you changed DNS hoping for speed but nothing feels different, it probably wasn't the bottleneck. The real benefit is usually privacy or content filtering, not speed. If speed does feel better, great — keep it. If not, switching back costs nothing.