What Is DNS and How Does It Affect Internet Speed?
DNS (Domain Name System) is the internet's phone book. Every time you type a web address or click a link, your device asks a DNS server to translate that human-readable name into a numerical IP address your computer can actually connect to. The time that lookup takes — typically 10 to 200ms — is added to every new connection your browser makes. A slow DNS server makes browsing feel sluggish even on a fast internet connection, because the delay happens before a single byte of page content arrives.
Understanding how DNS works, which public resolvers perform best, and how to switch to a faster one is one of the simplest and most underutilized connection improvements available — and it costs nothing.
How DNS Works Step by Step
- Browser request: You type "example.com" and press Enter. Your browser needs an IP address, not a domain name.
- Local cache check: Your OS checks whether it recently resolved this name. If yes, it uses the cached result instantly with zero network delay.
- Stub resolver query: If not cached, your device sends a query to its configured DNS resolver (usually your ISP's or the one configured in your router).
- Recursive resolution: If the resolver does not have the answer cached, it works through the DNS hierarchy — root servers, TLD servers (.com, .net, etc.), and finally the authoritative server for the specific domain.
- Response returned: The IP address is returned to your device and cached for a period specified by the domain's TTL (Time to Live).
- Connection established: Your browser connects to the IP address and loads the page.
This entire process typically takes 10–200ms. For a page that loads 60 separate resources (scripts, images, fonts, APIs), each new domain requires its own DNS lookup. Slow DNS multiplies.
Does DNS Affect Your Speed Test?
No — not directly. Speed tests measure your connection's bandwidth (how much data per second) and latency to a specific server. DNS resolution speed does not appear in your speed test results. However, DNS affects:
- Time to first byte: How quickly a page starts loading after you click a link
- Perceived browsing speed: On sites that load many third-party resources (ads, fonts, analytics), slow DNS adds up noticeably
- Reliability: If your ISP's DNS server goes down, you effectively lose internet access even though your physical connection is fine — all name lookups fail
- Privacy: Your DNS resolver sees every domain name you query; ISPs can log this data
DNS Resolver Performance
These figures represent median query times in globally aggregated benchmarks. Actual performance varies significantly by your geographic location and ISP. Your ISP's DNS may actually be faster than any public resolver if the servers are geographically close to you — or significantly slower if they are poorly maintained. The only way to know is to benchmark them from your specific location.
Popular DNS Resolvers Compared
| Provider | Primary | Secondary | Speed | Privacy | Filtering |
|---|---|---|---|---|---|
| Cloudflare | 1.1.1.1 | 1.0.0.1 | Fastest globally | Strong (no logs, audit) | None (use 1.1.1.2 for malware) |
| 8.8.8.8 | 8.8.4.4 | Very fast globally | Moderate (Google logs) | None | |
| Quad9 | 9.9.9.9 | 149.112.112.112 | Fast globally | Strong (Swiss privacy law) | Malware blocking enabled |
| OpenDNS (Cisco) | 208.67.222.222 | 208.67.220.220 | Good | Moderate (logs queries) | Customizable with account |
| NextDNS | varies (account) | varies | Good | Strong with account | Highly customizable |
| ISP default | Auto-assigned | Auto-assigned | Variable | Typically low | None or court-mandated blocks |
DNS-over-HTTPS and DNS-over-TLS
Standard DNS queries are sent in plain text — anyone between your device and the DNS server can see every domain name you look up. DNS-over-HTTPS (DoH) and DNS-over-TLS (DoT) encrypt DNS queries, preventing ISPs and eavesdroppers from seeing your lookups.
- DNS-over-HTTPS (DoH): Tunnels DNS queries inside HTTPS traffic on port 443. Supported natively in Firefox, Chrome, and Windows 11. Set up in browser settings or system network settings.
- DNS-over-TLS (DoT): Uses a dedicated port (853) with TLS encryption. Configured in operating system settings or on routers. Used on Android 9+ (Private DNS setting).
Cloudflare (1.1.1.1), Google (8.8.8.8), and Quad9 all support both DoH and DoT. For most users, enabling DoH in their browser is the easiest step toward encrypted DNS.
How to Change Your DNS
On your router (recommended — affects all devices)
- Open your browser and go to your router's admin panel (typically 192.168.1.1 or 192.168.0.1)
- Log in with your admin credentials
- Navigate to WAN settings, Internet settings, or Advanced network settings
- Find the DNS server fields (sometimes labeled "Primary DNS" and "Secondary DNS")
- Enter your preferred DNS addresses (e.g., 1.1.1.1 and 1.0.0.1 for Cloudflare)
- Save and restart the router
On Windows
- Open Settings → Network & Internet → Change adapter options
- Right-click your active connection → Properties
- Select "Internet Protocol Version 4 (TCP/IPv4)" → Properties
- Select "Use the following DNS server addresses"
- Enter your preferred DNS server addresses
- Click OK and close
On macOS
- Open System Preferences → Network
- Select your active connection → Advanced → DNS tab
- Click the + button to add DNS server addresses
- Enter your preferred addresses and remove the old ones
- Click OK → Apply
On Android
- Open Settings → Network & internet → Private DNS
- Select "Private DNS provider hostname"
- Enter the DoT hostname (e.g.,
1dot1dot1dot1.cloudflare-dns.comfor Cloudflare) - Tap Save
When DNS Change Helps Most
DNS switching has the most noticeable impact in these scenarios:
- Your ISP's DNS is slow: Some ISPs run poorly maintained DNS infrastructure with query times above 100ms. A switch to Cloudflare or Google reduces this to 10–20ms.
- Your ISP's DNS is unreliable: If you occasionally experience "website not found" errors on sites you know are up, your ISP's DNS may be dropping queries intermittently. A public resolver provides more reliable uptime.
- You browse many different domains: Sites that load dozens of unique third-party domains benefit more from fast DNS than single-domain applications.
- You want content filtering without special software: Quad9 blocks known malware domains. Cloudflare 1.1.1.2 blocks malware. These provide a layer of protection at the DNS level without installing anything.
For most users in well-connected areas, the difference between a good public resolver and their ISP's resolver is modest — 10–30ms per lookup. For users with slow or unreliable ISP DNS, the improvement can be meaningful and immediately noticeable.
How to Benchmark DNS from Your Location
The benchmark values above are global medians. Your results will differ. To measure DNS performance from your specific connection:
- DNS Benchmark (Windows): GRC.com's DNS Benchmark tool tests dozens of resolvers from your actual location and ranks them by performance
- namebench (macOS/Windows/Linux): Google's open-source DNS benchmarking tool; tests your real browser history patterns against multiple resolvers
- dnsperf.com: Web-based benchmark showing global and regional resolver performance trends