What Is a DNS Resolution Failure (and How to Fix It)

If you see an error like "Server not found," "This site can’t be reached," or "DNS_PROBE_FINISHED_NXDOMAIN," the problem isn't the website itself, but your computer's ability to *find* it. This is a DNS error.

What Is DNS?

Think of the **Domain Name System (DNS)** as the internet's phonebook. You type in a friendly website name (like google.com), and DNS translates that into a computer-friendly IP address (like 172.217.14.228). Your browser then connects to that IP address.

A "DNS resolution failure" means your computer asked the phonebook for the IP address, and the phonebook couldn't find a listing for that domain. The site might be "UP" (our tool would say so), but your computer can't find its address.

How to Fix DNS Errors (For Visitors)

This is almost always a client-side (your computer) or ISP-level problem. Here are the steps to fix it, from easiest to most advanced.

1. Clear Your Browser Cache

Your browser might be holding on to an old, bad DNS record. Clearing your cache forces it to look for a fresh one.

2. Flush Your Local DNS Cache

Your operating system (Windows, Mac, etc.) also keeps a DNS cache. Flushing it can solve the problem.

  • On Windows: Open Command Prompt and type ipconfig /flushdns and press Enter.
  • On Mac: Open Terminal and type sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder and press Enter.

3. Change Your DNS Resolvers

By default, you use your Internet Service Provider's (ISP) DNS servers, which can sometimes be slow or have problems. You can switch to free, fast, public DNS servers like Google's or Cloudflare's.

  • Google DNS: 8.8.8.8 and 8.8.4.4
  • Cloudflare DNS: 1.1.1.1 and 1.0.0.1

You can change these in your computer's network settings or, for a whole-home fix, in your Wi-Fi router's admin panel.

4. Restart Your Router

Your router also has a DNS cache. Turning it off and on again (the classic fix) will clear it and force it to get fresh records, which can resolve the issue.

How to Fix DNS Errors (For Site Owners)

If our tool also says your site is down, and you suspect a DNS issue, the problem is on your end. This is a critical issue that makes your site unavailable to *everyone*.

  • Check Your Domain's NS Records: Log in to your domain registrar (where you *bought* the domain name, like GoDaddy, Namecheap, etc.). Check that your "Nameservers" (NS records) are pointing to the correct place. They should be pointing to your web host (e.g., ns1.bluehost.com) or your DNS provider (e.g., ns1.cloudflare.com).
  • Check Your "A" Record: Log in to your DNS provider (this is often your web host). Find your DNS settings and check the "A" record for your main domain (represented by @). It *must* be pointing to the correct IP address provided by your web host. A typo here will take your site offline.
  • Wait for Propagation: If you just changed your nameservers or A record, you have to wait. DNS changes are not instant and can take anywhere from 30 minutes to 48 hours to "propagate" across the entire internet.