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What is DNS Lookup Failure?

Published in Networking 3 mins read

A DNS lookup failure occurs when your computer can't translate a website's domain name (like "example.com") into its corresponding IP address, preventing you from accessing the website. It's analogous to not being able to find a phone number in a phone book when you know the person's name.

Understanding DNS and Lookups

To better understand the failure, it's important to know what DNS and a DNS lookup are:

  • DNS (Domain Name System): This is essentially the internet's phonebook. It translates human-readable domain names into IP addresses that computers use to locate websites and other online resources.
  • DNS Lookup: This is the process your computer goes through to find the IP address associated with a domain name. Your computer queries a DNS server, which then searches its records (or queries other DNS servers) until it finds the correct IP address.

Causes of DNS Lookup Failure

Several factors can contribute to a DNS lookup failure:

  • Incorrect DNS Server Address: Your computer might be configured to use an incorrect or outdated DNS server address.
  • DNS Server Unavailability: The DNS server your computer is trying to use might be temporarily down or experiencing issues.
  • Network Connectivity Problems: A problem with your internet connection can prevent your computer from reaching a DNS server.
  • Firewall Issues: Your firewall might be blocking DNS queries.
  • Browser Issues: Sometimes, the browser itself might have issues performing DNS lookups.
  • Domain Name Registration Issues: While less common, the domain name itself might have expired, be suspended, or have incorrect DNS records.
  • Router Problems: Your router may have an incorrect DNS setting or be experiencing technical issues.

Common Error Messages

You might encounter various error messages when a DNS lookup fails, including:

  • "DNS server not available"
  • "Server DNS address could not be found"
  • "DNS_PROBE_FINISHED_NXDOMAIN"
  • "ERR_NAME_NOT_RESOLVED"

Troubleshooting Steps

Here are some steps you can take to troubleshoot a DNS lookup failure:

  1. Check Your Internet Connection: Make sure you have a stable internet connection.
  2. Restart Your Router and Computer: This can often resolve temporary network glitches.
  3. Flush Your DNS Cache: This clears out old DNS records that might be causing problems. On Windows, open Command Prompt and type ipconfig /flushdns. On macOS, open Terminal and type sudo dscacheutil -flushcache; sudo killall -HUP mDNSResponder.
  4. Change Your DNS Server: Try using a public DNS server like Google DNS (8.8.8.8 and 8.8.4.4) or Cloudflare DNS (1.1.1.1 and 1.0.0.1). You can change these settings in your network adapter settings.
  5. Disable Firewall or Antivirus Temporarily: In rare cases, these programs might be blocking DNS queries. Test if disabling them resolves the issue. If so, you'll need to configure them to allow DNS traffic.
  6. Check Your Browser Settings: Make sure your browser isn't configured to use a proxy server that's causing problems.
  7. Contact Your ISP: If none of the above steps work, the problem might be with your internet service provider (ISP).

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