How to Flush your DNS Cache on your computer

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Flushing your DNS cache is a way to troubleshoot DNS lookup issues and web page resolving issues from your computer.

The reason to flush DNS Cache is to ensure that your cache has the latest correct data. It is important to do this when there are server changes, moves or updates, or you are relocating your hosting or email to a new server, ip address or a new server hosting company.

Typically, DNS Cache is something that is handled between your PC and the DNS server it is attached to. However, devices such as firewalls may also cache DNS entries on behalf of your PC. These devices may need to be flushed as well.

How to Flush your DNS cache on Windows PC

  • Get to the command prompt. You can do this by click on on >Start>Run and typing "CMD" and pressing return. This should open a black window.
  • Within the window, type ipconfig /flushdns and press return.
  • Ping the website or hostname you are having an issue with. The ping will return the ip address that is associated with the DNS name.

How to speed up lookup performance

  • Usually, the reason people have to flush their DNS is because the TTL (Time to Live) is set too high on their firewall or on the DNS server that they are pointed to. Back in the old days of the Internet there were not a lot of DNS changes, so the DNS default is set to 3 days. Often, equipment is set to use this as a default because this is the Internet standard. Nowadays this is too long because server administrators are moving around and updating servers on a regular basis.
  • To improve performance, you can lower the TTL on these systems. Setting your DNS cache to 4-8 hours is a reasonable amount of time.
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