DNS Update does not work – how to flush your windows/linux client

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When transfering a Domain to a new Server or reconfiguring the IP of the Domain DNS entries of a Domain you are facing the problem, that you have to wait that the new DNS entry is being changed and spread on all DNS Servers.

Some operating system will not “obey” the DNS standards and will cache the old DNS records.

Refresh/flush the DNS Cache of your windows workstation

Even if everything is properly setup on the server side, your Windows workstation will not correctly see the change.

If you don’t want to reboot the workstation you will have to clear the workstations internal cache so it will query the DNS resolver again  and hopefully get the correct IP. In order to do this open the windows shell command prompt (Start/Run – and type “cmd”) and type in the following command:

ipconfig /flushdns

So your command should look like this:

C:\\user>ipconfig /flushdns

Windows IP Configuration

Successfully flushed the DNS Resolver Cache.

Now you cleared the entire local dns cache.

Tipp: If a server already shows up the new IP but your windows client doesn’t, you may consider restarting your Router in order to refresh your Router/Provider DNS Cache.

Refresh/flush the DNS Cache of your Linux workstations

Normally Linux workstations are not facing these problemss, as the linux resolver will follow the standards and query for the new IP once the TTL will expire. Anyway – if you want to clear the DNS cache even in this case you have to restart the DNS service.

If you are using bind on Debian based systems, type in:

/etc/init.d/bind9 restart

or on RedHat based systems:

/etc/init.d/named restart

Same Tip here: If a server already shows up the new IP but your client doesn’t, you may consider restarting your Router in order to refresh your Router/Provider DNS Cache.

There is another hot Tip: If your Provider isn’t quite fast in changing its DNS Server entries, you may change your local settings (windows machines).

  1. Find the file “hosts” in your windows folder.
  2. open the file with an editor (i like notpad++ ). Be sure to open the file in Administrator Mode (right click) otherwise you won’t be able to save the file.
  3. Add the Entry “xxx.xxx.xxx.xxx yourdomain.com”  well, xxx.xxx.xxx.xxx is your IP.
  4. Save and close the file

That’s it, your local maschine is no directly directing the domain to the IP – without checking the DNS Server.

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