I think GP means it is notable that, in 2016, the zone list for NK is so small that it can be perused in mere seconds due to its short length (as compared to any other country).

The interesting parts are not by design. Yes, you can query the server, that's the expected behavior. But:

1. It's not normal to allow global zone transfers on most country-code nameservers, which enables other Internet users to get the full list of registered domains. Yes, some do it: https://github.com/mandatoryprogrammer/TLDR/blob/master/READ...

2. It's not normal for the list of all the domains registered to a TLD to be readable by a human in a short timeframe. If you could get a list of all .com or .co.uk domains, you probably could not read all the domains which start with 'aa', much less the complete list.