Refreshing Your DNS Cache
Written by: Will Kruss on 02 December 2014 12:15 PM
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When you change the name servers the best way to test if the change is correct is to check at http://www.mxtoolbox.com
Visit their site and type in the domain. This will return the MX record. You can also check the A record by then clicking on 'dns lookup' which will tell you the IP address your site is actually resolving to at the moment.
Note: If you run a DNS Check and are using the ns1.controlmyvps.com.au / ns2.controlmyvps.com.au name servers other name servers in the controlmyvps.com.au domain which are not functional will appear, this can safely be ignored as those other name servers are not authoritative for your domain (only the ones you specify at your registrar are authoritative). Always ensure when changing DNS servers at your registrar that you remove the old DNS servers, failure to do so will result in sporadic changes in IP address resolution.
Often after you change name servers the change will not propogate immediately to your computer. So while mxtoolbox.com reports the correct IP address, you may still be resolving the domain to an old IP address, or no IP address at all.
If after 4 hours this is still occurring, there are three things you can look at.
This is where your browser remembers the IP address for your domain, to fix this simply close your browser and all browser windows entirely.
Local DNS Caching
This is where your computer remembers the IP address for your domain. First close all browser windows. Then open a command prompt (start -> run and type: cmd), then type: ipconfig /flushdns
Then type: ping domain.com
If it returns the new IP address, you can now restart your browser and all should work.
If it returns the old IP address then your DNS servers (provided by your ISP) are caching.
ISP DNS Caching
If your ISP is caching the best thing to do is just to wait, within 24 hours the cache entry should expire and you should be able to access it on the new IP address. If you are in a hurry you can bypass your ISPs DNS cache by: