Zone Signing Key (ZSK)

What Is a Zone Signing Key?

A Zone Signing Key (ZSK) is a cryptographic key used in DNSSEC (Domain Name System Security Extensions) to digitally sign the individual DNS records within a specific DNS zone.

The ZSK ensures that when someone performs a DNS lookup, the information returned from that zone can be verified as authentic and unaltered. It is part of the digital signature system that keeps the DNS secure and prevents attackers from inserting false data.

What's the Role of ZSK in DNSSEC?

DNSSEC uses two types of keys to maintain trust and verify authenticity: the Zone Signing Key (ZSK) and the Key Signing Key (KSK). The ZSK is responsible for signing the actual DNS resource records, such as A, MX, TXT, and NS entries.

When a DNS query is made, the resolver checks the digital signature created by the ZSK against the corresponding public key that is published in the zone’s DNSKEY record. If the signature matches, it confirms that the data has not been tampered with.

The ZSK is typically shorter and rotated more frequently than the KSK, since it directly signs all the active DNS data in the zone. The KSK, on the other hand, signs only the ZSK, linking it into the broader DNSSEC trust chain.

Managing and Rotating ZSKs

Proper management of Zone Signing Keys is essential for maintaining secure and uninterrupted DNS service. Because the ZSK is used regularly to sign records, it can become a target for attackers. Rotating it on a regular schedule minimizes the risk of key compromise and helps maintain a healthy cryptographic posture.

If a ZSK is changed, the new key must be published in the zone’s DNSKEY record before the old one is retired. This ensures that resolvers can continue verifying signatures without disruption. Automation and DNSSEC-aware tools are often used to handle these rotations safely.

ZSKs and DMARCeye

While DMARCeye focuses on email authentication rather than DNSSEC management, it depends on accurate and secure DNS data. The presence of a valid ZSK helps guarantee that records like SPF, DKIM, and DMARC cannot be tampered with at the DNS level.

By monitoring authentication data and analyzing DNS integrity, DMARCeye provides the confidence that your domain’s protective measures are backed by a trusted DNS foundation secured with keys like the ZSK.