What is DNSSEC?
DNSSEC is a security extension for the current Domain Name System. DNSSEC significantly improves the security of the DNS system by reducing the risks that information can be changed or tampered with during transfer over the Internet. Most of the European country code top level domains are DNSSEC enabled.
How does it work?
The DNS system relies on a hierarchical chain of references to resolve a domain name query. When sending a query to the top level domain, it assumes that the response is correct and can be trusted.
Where can I find more information?
DNSSEC course by SIDN (.nl) (in English/Dutch)