DNSSEC stands for ‘Domain Name System Security Extensions’, and is a security addon to the current DNS system.
The purpose of DNSSEC is to introduce mechanisms that secure the DNS system to make it impossible to inject false answers to DNS lookups, which is possible in the current DNS system.
Most top level registries have already implemented DNSSEC support. Norid launched support for DNSSEC in the ‘no’ zone in 2014.
You can learn more about DNSSEC through the links in ‘USEFUL LINKS’.