It takes some time for the change to propagate. Depending on the central registry, they may update within five minutes or take a whole day to update. You can do an IP lookup to see if your name server settings have been propagated.
To do an IP lookup, follow these steps:
1. Log into your Dynadot account. 2. Click the "Domains" section link. 3. Then look for the "ip" link in the "Name Server" column for the domain you want to check. 4. Click on this link. This will pop up another window stating the IP status of your domain.