Have you ever had to switch the DNS on one of your domains and wanted to know if the rest of the world is seeing the change? It’s virtually impossible to test the change for every single person that might be making a request for your DNS entry, but with What’s My DNS Propagation Checker you can get a pretty good idea of whether the rest of the world is picking up the change.
This free service can query for A, AAAA, CNAME, MX, NS, PTR, SOA, and TXT records. They make the request from over 15 different locations spread out across the globe, and it could help you recognize issues faster than you would have ordinarily caught them. So anytime you’re wanting to monitor a DNS change this should help you out, and is definitely a service you’ll want to have tucked away in your bookmarks.