Quick Tips

Want to Learn How to Flush DNS? Here’s How

The following information will show you how to flush DNS on various operating systems. As you will see, the process is pretty straightforward. By flushing, you’ll be able to quicken subsequent requests to the same host. It also helps get rid of those annoying 404 errors. So guys, here is How to Flush DNS on various OS.

Windows Vista / Windows 7

For the latest versions of Windows, the process is as follows. Due to increased security on the part of the software, you must have administrator privileges to use the Run prompt.

Click the Start button and go to All Programs > Accessories > Command Prompt. Right click the command prompt application. Select “Run as Administrator”. Type “ipconfig /flushdns“. You can also type “cmd” at the Windows 7 / Vista Start menu search field.

Windows 98/NT/2000/XP

To clear the DNS cache, just do the following. Go to (Start > Run and type “cmd.exe” minus the quotes. Click OK. In the command line type “ipconfig /flushdns“.

Mac OS X

How to Flush DNS

If you are using Mac OS X Snow Leopard, do the following. Open a command terminal. After running the “dscacheutil -flushcache” command, the flushing will commence. For those with Mac OS X 10.5.1 or below, use the following procedure. Open a command terminal. Now, “lookupd -flushcache” has to be run.


If you are studying how to flush DNS on various operating systems, you may also want to know how it’s done on Linux. For those with the NSCD (Name Service Cache Daemon), open a command terminal as root. Run “/etc/init.d/nscd restart“.

Disabling the DNS Firefox Cache

This browser has a DNS cache distinct from computer’s client services. To disable it, the Firefox DNS plugin has to be downloaded and installed. After right clicking the Home button, choose “Customize”. Find the “DNS Cache”. Drag this alongside the Home button.

Click “Done” when you are finished. After clicking the “DNS Cache” menu button, the browser’s DNS cache will be disabled.
Users can also modify the DNS settings so it will expire in X number of seconds. Just type in the location bar “about:config”. Hit the Enter key. After right clicking a blank location and choose “New” and “Integer”.

Type “network.dnsCacheExpiration” for the preference name. The integer value should be 0. If you want to restore the value to the default, just type “3600”. As long as 0 is the integer value, Firefox’s DNS cache will expire automatically.

Overview of the DNS

DNS (Domain Name System) is a database that decodes URLs or a plain language web address to an IP address. DNS was developed because it is simpler to recall names like wwww.website.com than 123.456.789.10.

Usually, at least one server handles DNS queries or requests on a local computer network. It also conducts a quick-lookup function or caching. These functions help reduce the time required to fix domain lookups.

Other Information

For most users, the problem involves a local computer’s DNS storage requiring flushing or bad configuration. Sometimes a user will enter the wrong DNS server of their ISP (Internet service provider). If this happens, the Internet connection won’t work. Because of this reason, you need to make sure the right information is stored.

When you study how to flush DNS on various operating systems, keep in mind that Internet service providers have unique processes for configuration. Usually your ISP will utilize their address for the DNS server.

About the author


I am Vishal Gaikar, Engineer, Web Addicted, Living in Maharastra, India. Email Me @ vishal@techbucket.org

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