How DNSSEC works and why it matters

The Domain Name System (DNS) acts like the internet’s address book, translating domain names into IP addresses. Traditional DNS has no built-in security, leaving it vulnerable to attacks like cache poisoning and man-in-the-middle exploits. DNSSEC (Domain Name System Security Extensions), on the other hand, adds cryptographic protections to make DNS more secure.

According to Cloudflare, DNSSEC ensures website visitors that they’re directed to the correct destination—not a fraudulent one set up by attackers. It does this by adding digital signatures to DNS records, which verify their authenticity and prevent tampering. 

How DNSSEC adds security to DNS

DNSSEC builds on the existing DNS infrastructure by introducing cryptographic signatures for DNS records. It uses public-key cryptography, assigning each DNS zone a pair of keys: a private key to sign records and a public key to verify them. Cloudflare states that this creates a “chain of trust,” starting from the root DNS servers and extending to individual domain names.

The components include the zone signing key (ZSK) and the key signing key (KSK). The ZSK signs the zone’s DNS records, while the KSK signs the DNSKEY record containing the public ZSK. Together, they ensure that DNS responses can be trusted.

Here’s a simplified view of the signing process:

• Making keys: The zone administrator creates two types of keys—ZSK (for signing records) and KSK (for managing trust).
• Signing data: The ZSK is used to sign all DNS records in the zone, creating signatures saved in records.
• Sharing keys: The public versions of the ZSK and KSK are shared in DNSKEY records so others can verify the signatures.
• Building trust: A hash of the KSK is sent to the parent DNS zone as a DS (Delegation Signer) record. This links the child zone to the parent zone, creating a trusted connection.

The process ensures that DNS records can be verified at every level, from the root servers to the domain.

Read also: What is DNS? 

How DNSSEC validation works

1. Checking responses: When a DNSSEC-enabled resolver gets a DNS response, it makes sure it’s authentic.
2. Verifying signatures: It uses the public ZSK to check the digital signatures in the RRSIG record.
3. Validating keys: It confirms the DNSKEY record with the KSK and compares the KSK’s hash to the DS record from the parent zone.
4. Trust or block: If everything matches, the response is trusted. If something doesn’t match, the resolver assumes the response might be unsafe and may block access to protect users.

Why DNSSEC matters

DNSSEC provides several benefits that enhance online security:

• Protecting against attacks: It prevents DNS cache poisoning and man-in-the-middle attacks, ensuring users aren’t redirected to malicious sites.
• Verifying authenticity: By confirming the source of DNS data, DNSSEC ensures users connect to legitimate servers.
• Building trust: DNSSEC secures the foundation of online communications, making transactions and interactions more reliable.

Read also: What is a man-in-the-middle (MITM) attack? 

FAQs

Why does DNSSEC matter for email security?

DNSSEC supports protocols like DMARC (Domain-based Message Authentication, Reporting, and Conformance), SPF (Sender Policy Framework), and DKIM (DomainKeys Identified Mail) by ensuring that DNS records used for email authentication are secure. Without DNSSEC, attackers could manipulate DNS to impersonate domains and bypass email security measures.

Does DNSSEC affect email delivery?

When enabled, DNSSEC doesn’t interfere with email delivery but ensures that DNS records for email authentication (SPF, DKIM, DMARC) are valid. However, if DNSSEC validation fails, DNS responses may be blocked, potentially affecting services relying on those responses.

How do DNSSEC failures impact email security?

If DNSSEC validation fails (e.g., due to misconfiguration or expired keys), email authentication protocols relying on DNS may fail. This could result in legitimate emails being rejected or flagged as suspicious.

Is DNSSEC mandatory for email security?

While not mandatory, DNSSEC enhances email security by ensuring DNS integrity. Many organizations implement DNSSEC alongside SPF, DKIM, and DMARC for comprehensive email protection.

Learn more: HIPAA Compliant Email: The Definitive Guide