How long does my Internet Service Provider keep my old DNS records?
Saturday, December 26th, 2009
If you are going to transfer your website from one web hosting provider to another, then your old DNS (Domain Name Server) records are still cached for a given time by your ISP (and all other DNS servers around the globe). How long it takes for you until your domain resolves (also known as DNS propagation) to the new location can be figured out by following the steps outlined below:
- In Microsoft Windows go to your “Start Menu”.
- Choose “Run …”.
- Type within the text field “cmd”.
- Magically a black box appears, at the command prompt type the following:
- nslookup [enter]
- set debug [enter]
- www.yourdomain.tld [enter] <= Change this to the domain you are moving from webhost
The answer we are looking for can be found under the headline …. “ANSWERS” just below the headline “QUESTIONS”. 
We are specifically interested in the value TTL (Time To Live). These are the seconds it takes before your ISP (Internet Service Provider) will refresh the DNS records that belongs to your domain.
Below an illustrating picture:
