You just performed a name server change for your domain name and your provider has said that it could take up to 24-48 hours for the new name servers to propagate around the world. The clock starts ticking and you are wondering if you are seeing the website from your new hosting provider or the old one. The problem is both the websites are identical. You can try ‘cheap’ tricks like loading a file that is only available on the new server or use this online tool to find out if any records including A, AAA, PTR, SOA, CNAME, MX and others have propagated over the world.
whatsmydns.net is an online service that allows you to instantly perform a DNS lookup to check a hostnames current IP Address and other DNS information against a selection of random name servers around the world. This is especially useful to check the current state of DNS propagation after making changes to your domains zones.
Check out whatsmydns.net