Try 1984.is and puck.nether.net . Config. them as your MiAB Custom DNS and at your BOX domain registar nameservers panel, as your secundary (slave) DNS servers.
Additionally, if your domains registar is Gandi.net they offer you a ns6.gandi.net secundary DNS entry, too
- I setup those three ones by default at each MiaB I build and all of them work as expected.