DNS Cache Pollution

Standard

Your DNS cache stores the locations (IP addresses) of webservers that contain pages which you have recently viewed. If the location of the web server changes before the entry in your DNS cache updates, you will be unable to access the site.

If you encounter a large number of HTTP 404 Error, you may need to clear your DNS cache. Once you clear your DNS cache, your computer will query nameservers for the new DNS information.

Windows 98/NT/2000/XP Flush DNS

Flushing the DNS on Windows is an easy process, outlined below is the steps that should be run if you wish to clear your DNS cache.

  1. Open up a command prompt (Start > Run > cmd.exe > OK).
  2. Type in the command ipconfig /flushdns
Windows XP Flush DNS - Step 1 - Click Start Windows XP Flush DNS - Step 2 - Click All Programs Windows XP Flush DNS - Step 3 - Click Accessories and run Command Prompt Windows XP Flush DNS - Step 4 - Command Prompt will open Windows XP Flush DNS - Step 5 - Type 'ipconfig /flushdns' Windows XP Flush DNS - Step 6 - The DNS is now flushed Windows XP Flush DNS - Step 7 - Type 'exit' to close the Command Prompt

Windows Vista / Windows 7 Flush DNS

Flushing DNS on newer versions of Windows is almost as easy as the earlier versions but due to Microsoft’s security additions you must run the command prompt with administrator privileges.

  1. Click the start button and navigate to the command prompt (Start > All Programs > Accessories > Command Prompt)
  2. Make sure that you right click on the command prompt application and choose “Run as Administrator”
  3. Type in the command ipconfig /flushdns
Windows Vista / Windows 7 Flush DNS - Step 1 - Click Start and click All Programs Windows Vista / Windows 7 Flush DNS - Step 2 - Click Accessories Windows Vista / Windows 7 Flush DNS - Step 3 - Click Command Prompt Windows Vista / Windows 7 Flush DNS - Step 4 - Command Prompt will open Windows Vista / Windows 7 Flush DNS - Step 5 - Type 'ipconfig /flushdns' Windows Vista / Windows 7 Flush DNS - Step 6 - The DNS is now flushed Windows Vista / Windows 7 Flush DNS - Step 7 - Type 'exit' to close the Command Prompt

Note: It is also possible to type in cmd into the Windows Vista / Windows 7 start menu search field and then right click on the cmd.exe result instead of having to navigate through the various sub menus.

Windows 8 / Windows 8.1 Flush DNS

Flushing the DNS cache on Windows 8 and Windows 8.1 is a very easy process. Due to system security permissions, you must ensure that you run the command prompt as an administrator user.

  1. Ensure that you’re on the Windows 8 Start Screen.
  2. Simply type cmd and the Windows search bar will appear on the right hand side with search results.
  3. Right click on Command Prompt and click Run as administrator.
  4. Type in the command ipconfig /flushdns
Windows 8 / Windows 8.1 Flush DNS - Step 1 - Begin on the Windows 8 Start Screen Windows 8 / Windows 8.1 Flush DNS - Step 2 - Type 'cmd' Windows 8 / Windows 8.1 Flush DNS - Step 3 - Right click 'Command Prompt' and choose 'Run as administrator' Windows 8 / Windows 8.1 Flush DNS - Step 4 - Command Prompt will open Windows 8 / Windows 8.1 Flush DNS - Step 5 - Type 'ipconfig /flushdns' Windows 8 / Windows 8.1 Flush DNS - Step 6 - The DNS is now flushed Windows 8 / Windows 8.1 Flush DNS - Step 7 - Type 'exit' to close the Command Prompt
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One thought on “DNS Cache Pollution

  1. Hi,

    This is a problen of the operator/admin from the website. He have to reduce TTL of the IP address, before switching it to another IP.
    It must be done at least on TTL period before the planed step.

    Like

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