Yes, that’s called Round-Robin Load Balancing.

To get more specific, your DNS provider spins up a large number of DNS resolvers out in the world on a CDN network that resolves clients to the most geographically convenient server(s) at any point in time based on the GeoIP info of your public IP.

Once you resolve one set of addresses at any given time, it catches your request, so the next time you ask these DNS servers for something you’ll get a response right back from them as fast as possible.

You constantly checking is just going to show this. It’s quite normal.