NSEC (Next Secure) records are a crucial component of DNSSEC that provide authenticated denial of existence. They prove that a particular domain name or record type does not exist in a DNS zone, preventing attackers from spoofing non-existent records.

How NSEC Records Work:

• Create a chain of all existing domain names in a zone
• Each NSEC record points to the next domain name in alphabetical order
• Include a list of record types that exist for the current domain
• Are signed with RRSIG records to ensure authenticity
• Allow resolvers to prove non-existence of queried names or types

NSEC vs NSEC3:

Security Benefits:

• Prevents cache poisoning attacks with non-existent records
• Ensures integrity of negative DNS responses
• Provides cryptographic proof of non-existence
• Enables secure validation of NXDOMAIN responses