What is DNS flushing?
DNS flushing is the process of clearing the Domain Name System (DNS) cache on your device. Most devices store records retrieved from DNS servers in their cache to avoid repeat queries in the future. However, because anyone with access to this cache can see your past online activity or redirect you to dangerous websites (DNS spoofing), it is important that you flush the DNS cache periodically.
See also: DNS query, DNS filtering, DNS cache, DNS resolution, DNS sinkhole
What does DNS flushing do?
Flushing DNS removes old or incorrect DNS entries from your device’s cache. Once the cache is cleared, your device must ask DNS servers for up-to-date information. This can fix connection problems, remove inaccurate records, and help ensure you reach the correct website.
Why you should flush your DNS
You might need to flush your DNS cache for several reasons:
- Fixing outdated or incorrect records
If a website changes servers or IP addresses, your device may still rely on an old cached entry. Flushing forces your device to get the new, correct address. - Improving security
Clearing the cache can remove potentially spoofed or manipulated DNS records created by malicious redirects. - Resolving connection issues
Sometimes your device stores broken or partial DNS entries. Flushing the cache often restores normal access to websites. - Protecting privacy
Your DNS cache contains a small history of websites your device resolved. Clearing it helps reduce local tracking.
Is flushing your DNS safe?
Yes, flushing your DNS is safe and does not affect your device’s apps, files, or operating system. The only change is that your device must perform new DNS lookups after the flush, which may make the next few website visits slightly slower until the cache fills again.
How can I flush my DNS?
The steps vary depending on the operating system, but the process is quick and simple. You run a short command that clears the DNS cache immediately.
For detailed instructions, see our guide on how to flush your DNS.
Real uses for DNS flushing
- Preventing DNS spoofing: If criminals gain access to your DNS cache, they can secretly redirect innocent URLs to fake websites. This technique is commonly used to obtain account credentials or penetrate secure corporate networks. Flushing the DNS cache clears out entries that may have been tampered with.
- Resolving web access problems: Clearing cookies and flushing bad DNS entries effectively resets your internet connection, letting you try to access websites with a clean configuration.
- Connecting to relocated websites: Outdated DNS entries can stop you from connecting to a website’s new domain. Flushing your DNS cache solves this problem.
- Protecting your privacy: Your DNS cache contains a record of all your DNS queries — where you went and what you were interested in online. Flushing your DNS records prevents anyone from getting their hands on this information.
- Troubleshooting connectivity issues: DNS problems can cause slow loading times, random timeouts, or some websites working while others fail. When you are troubleshooting these connectivity issues, flushing DNS is a simple, low-risk step. It removes any cached entries that might be pointing your device in the wrong direction and forces it to get fresh records from the DNS servers.
