Zonemaster.se: Run domain test
https://zonemaster.se/en/run-test
DNS | ToolThe zonemaster website runs various checks on the name servers for a zone. It covers various basics like IP reachability, consistency, diversity in the operators, various correctness tests like QNAME case insensitivity, and checking the quality of the EDNS setup. It is similar to Zonemaster by cz.nic.