What is DNSSEC?

At first DNSSEC stands for Domain Name System Security Extensions it aimed at strengthening trust in the internet by helping to protect users from redirection to fraudulent websites addresses. In such away malicious activities like pharming and cache poisoning attacks can be prevented.

Also it authenticates the resolution of IP addresses with a cryptographic signature. It's make sure that answers provided by the DNS server are valid and authentic.

Thank you for letting us know.

I will add that it is also a major PITA when moving website.

Source:

https://en.m.wikipedia.org/wiki/Domain_Name_System_Security_Extensions#:~:text=The%20Domain%20Name%20System%20Security,Internet%20Protocol%20(IP)%20networks.