How Cloud DNS DNSSEC Trust and KSK Rotation Work

DNSSEC Chain of Trust and Zero Downtime KSK Rotation

An enterprise hosts its primary domain in a Google Cloud DNS public managed zone. A security engineer must configure Domain Name System Security Extensions (DNSSEC) to protect client resolvers from DNS spoofing and cache poisoning attacks. The solution must establish a verified chain of trust with the third-party domain registrar and define a zero-downtime rotation procedure for the Key Signing Key (KSK).

Which procedure should the security engineer implement?

Create a Cloud DNS private peering zone linked to an external resolver, configure DNSSEC validation rules within the producer VPC, and submit the generated DNSSEC certificate to the registrar via TLS.

Enable DNSSEC on the Cloud DNS managed zone, retrieve the generated Delegation Signer (DS) record data, submit the DS record to the domain registrar, and when rotating the KSK, add the new KSK, publish the new DS record at the registrar, wait for the DS TTL to expire, and then delete the old KSK.

Enable DNSSEC on the Cloud DNS managed zone, immediately delete the default KSK to generate a new key pair, upload the new public key directly to Cloud DNS response policies, and leave registrar DS configurations blank.

Enable DNSSEC on the Cloud DNS managed zone, export the Zone Signing Key (ZSK) public key string, add the raw ZSK as an NS record at the registrar, and rotate the ZSK every 30 days by modifying registrar settings.

Explanations

Create a Cloud DNS private peering zone linked to an external resolver, configure DNSSEC validation rules within the producer VPC, and submit the generated DNSSEC certificate to the registrar via TLS.

What this option proposes

This option attempts to secure public DNS resolution by setting up private DNS peering zones and relying on internal VPC DNS validation.

Why it doesn't meet the requirement

Private vs. public scope: DNS peering zones route DNS queries privately between VPC networks inside Google Cloud; they do not publish or secure public DNS records on the internet.
Irrelevant to external resolvers: Private zone security settings have zero effect on external public resolvers querying the organization's public domain.
Misunderstanding of DNSSEC records: DNSSEC uses DNS resource records (DS, DNSKEY, RRSIG) rather than TLS certificates to establish cryptographic authenticity.

Key limitations

Private peering zones cannot serve public internet DNS traffic.
Registrars accept DS records (digest hashes of KSKs), not TLS certificates.
Peering configurations only handle internal name resolution pathways between consumer and producer VPC networks.

This answer would be correct if

The objective was to route private service requests between two Google Cloud VPC networks or Apigee producer networks using internal DNS namespaces.

View source documentation

Enable DNSSEC on the Cloud DNS managed zone, retrieve the generated Delegation Signer (DS) record data, submit the DS record to the domain registrar, and when rotating the KSK, add the new KSK, publish the new DS record at the registrar, wait for the DS TTL to expire, and then delete the old KSK.

What DNSSEC in Cloud DNS is

Domain Name System Security Extensions (DNSSEC) provides cryptographic authentication of DNS data to prevent DNS spoofing, cache poisoning, and man-in-the-middle tampering. In Google Cloud DNS, enabling DNSSEC causes the service to automatically generate Key Signing Keys (KSK) and Zone Signing Keys (ZSK), sign the resource record sets (RRsets) with RRSIG records, and generate Delegation Signer (DS) records.

How it meets the requirements

Cryptographic verification: Enabling DNSSEC signs zone records with digital signatures, allowing validating resolvers to cryptographically verify response authenticity.
Establishing chain of trust: Extracting the generated DS record details (key tag, algorithm, digest type, and digest) from Cloud DNS and provisioning them at the parent domain registrar connects the parent zone's trust anchor to the managed zone's KSK.
Zero-downtime KSK rotation: Following a staged double-signature rollout ensures continuity. The new KSK is introduced, the new DS record is published at the registrar, sufficient time is allowed for cached DS records to expire across global recursive resolvers (TTL expiration), and only then is the retired KSK removed.

Key advantages

Automated ZSK management: Cloud DNS handles frequent Zone Signing Key rotations automatically in the background without registrar involvement.
Tamper resistance: Cryptographically seals domain records against recursive cache poisoning attacks.
High availability during key maintenance: Prevents resolution failures (SERVFAIL responses) during planned cryptographic key lifecycle events.

Why this is optimal

This approach strictly complies with RFC specifications and DNSSEC standards for establishing a verifiable delegation chain while preventing service outages during public key transitions.

View source documentation

Enable DNSSEC on the Cloud DNS managed zone, immediately delete the default KSK to generate a new key pair, upload the new public key directly to Cloud DNS response policies, and leave registrar DS configurations blank.

What this option proposes

This option suggests deleting the initial KSK immediately after enabling DNSSEC and using Cloud DNS response policies instead of registrar DS records.

Why it doesn't meet the requirement

Missing chain of trust: Without publishing a DS record at the registrar, recursive resolvers validating from the root zone will treat the zone as insecure (unsigned) or fail validation if trust anchors mismatch.
Misuse of response policies: Cloud DNS response policies are designed for private VPC split-horizon and query interception rules, not for public DNSSEC trust anchor distribution.
Outage risk: Deleting active signing keys abruptly without staged rollout causes validation failures for querying clients.

Key limitations

Response policies apply exclusively within associated VPC networks, not to public internet resolvers.
Leaving registrar DS configurations blank fails to prevent public DNS spoofing and cache poisoning.
Deleting an active KSK immediately breaks cryptographic continuity.

This answer would be correct if

The organization were configuring internal VPC response policies to redirect internal queries to a private endpoint without public DNSSEC validation.

View source documentation

Enable DNSSEC on the Cloud DNS managed zone, export the Zone Signing Key (ZSK) public key string, add the raw ZSK as an NS record at the registrar, and rotate the ZSK every 30 days by modifying registrar settings.

What this option proposes

This option suggests exporting the raw Zone Signing Key (ZSK) public key into registrar NS records and manually coordinating ZSK rotations with the registrar.

Why it doesn't meet the requirement

Incorrect key type for registrar delegation: Registrars do not store or evaluate ZSKs; they store Delegation Signer (DS) records that hash the Key Signing Key (KSK).
Misplaced cryptographic records: NS (Name Server) records define authoritative nameservers, not cryptographic public keys. Publishing key strings into NS record sets corrupts zone delegation.
Unnecessary operational overhead: Cloud DNS automatically manages and rotates ZSKs internally without requiring any registrar updates.

Key limitations

Fails to establish a valid DNSSEC chain of trust, leaving validating resolvers unable to verify records.
Conflates the responsibilities of the KSK (delegation authentication) and ZSK (zone record signing).
Creates severe operational burden by attempting manual registrar management of automatic zone keys.

This answer would be correct if

The registrar required manual authoritative name server IP glue records rather than DNSSEC cryptographic delegation.

View source documentation

Last updated August 28, 2026Validated August 28, 2026

DNSSEC Chain of Trust and Zero Downtime KSK Rotation

Which procedure should the security engineer implement?

Explanations

Create a Cloud DNS private peering zone linked to an external resolver, configure DNSSEC validation rules within the producer VPC, and submit the generated DNSSEC certificate to the registrar via TLS.

What this option proposes

This option attempts to secure public DNS resolution by setting up private DNS peering zones and relying on internal VPC DNS validation.

Why it doesn't meet the requirement

Private vs. public scope: DNS peering zones route DNS queries privately between VPC networks inside Google Cloud; they do not publish or secure public DNS records on the internet.
Irrelevant to external resolvers: Private zone security settings have zero effect on external public resolvers querying the organization's public domain.
Misunderstanding of DNSSEC records: DNSSEC uses DNS resource records (DS, DNSKEY, RRSIG) rather than TLS certificates to establish cryptographic authenticity.

Key limitations

Private peering zones cannot serve public internet DNS traffic.
Registrars accept DS records (digest hashes of KSKs), not TLS certificates.
Peering configurations only handle internal name resolution pathways between consumer and producer VPC networks.

This answer would be correct if

The objective was to route private service requests between two Google Cloud VPC networks or Apigee producer networks using internal DNS namespaces.

View source documentation

Enable DNSSEC on the Cloud DNS managed zone, retrieve the generated Delegation Signer (DS) record data, submit the DS record to the domain registrar, and when rotating the KSK, add the new KSK, publish the new DS record at the registrar, wait for the DS TTL to expire, and then delete the old KSK.

What DNSSEC in Cloud DNS is

How it meets the requirements

Cryptographic verification: Enabling DNSSEC signs zone records with digital signatures, allowing validating resolvers to cryptographically verify response authenticity.
Establishing chain of trust: Extracting the generated DS record details (key tag, algorithm, digest type, and digest) from Cloud DNS and provisioning them at the parent domain registrar connects the parent zone's trust anchor to the managed zone's KSK.
Zero-downtime KSK rotation: Following a staged double-signature rollout ensures continuity. The new KSK is introduced, the new DS record is published at the registrar, sufficient time is allowed for cached DS records to expire across global recursive resolvers (TTL expiration), and only then is the retired KSK removed.

Key advantages

Automated ZSK management: Cloud DNS handles frequent Zone Signing Key rotations automatically in the background without registrar involvement.
Tamper resistance: Cryptographically seals domain records against recursive cache poisoning attacks.
High availability during key maintenance: Prevents resolution failures (SERVFAIL responses) during planned cryptographic key lifecycle events.

Why this is optimal

This approach strictly complies with RFC specifications and DNSSEC standards for establishing a verifiable delegation chain while preventing service outages during public key transitions.

View source documentation

Enable DNSSEC on the Cloud DNS managed zone, immediately delete the default KSK to generate a new key pair, upload the new public key directly to Cloud DNS response policies, and leave registrar DS configurations blank.

What this option proposes

This option suggests deleting the initial KSK immediately after enabling DNSSEC and using Cloud DNS response policies instead of registrar DS records.

Why it doesn't meet the requirement

Missing chain of trust: Without publishing a DS record at the registrar, recursive resolvers validating from the root zone will treat the zone as insecure (unsigned) or fail validation if trust anchors mismatch.
Misuse of response policies: Cloud DNS response policies are designed for private VPC split-horizon and query interception rules, not for public DNSSEC trust anchor distribution.
Outage risk: Deleting active signing keys abruptly without staged rollout causes validation failures for querying clients.

Key limitations

Response policies apply exclusively within associated VPC networks, not to public internet resolvers.
Leaving registrar DS configurations blank fails to prevent public DNS spoofing and cache poisoning.
Deleting an active KSK immediately breaks cryptographic continuity.

This answer would be correct if

The organization were configuring internal VPC response policies to redirect internal queries to a private endpoint without public DNSSEC validation.

View source documentation

Enable DNSSEC on the Cloud DNS managed zone, export the Zone Signing Key (ZSK) public key string, add the raw ZSK as an NS record at the registrar, and rotate the ZSK every 30 days by modifying registrar settings.

What this option proposes

This option suggests exporting the raw Zone Signing Key (ZSK) public key into registrar NS records and manually coordinating ZSK rotations with the registrar.

Why it doesn't meet the requirement

Incorrect key type for registrar delegation: Registrars do not store or evaluate ZSKs; they store Delegation Signer (DS) records that hash the Key Signing Key (KSK).
Misplaced cryptographic records: NS (Name Server) records define authoritative nameservers, not cryptographic public keys. Publishing key strings into NS record sets corrupts zone delegation.
Unnecessary operational overhead: Cloud DNS automatically manages and rotates ZSKs internally without requiring any registrar updates.

Key limitations

Fails to establish a valid DNSSEC chain of trust, leaving validating resolvers unable to verify records.
Conflates the responsibilities of the KSK (delegation authentication) and ZSK (zone record signing).
Creates severe operational burden by attempting manual registrar management of automatic zone keys.

This answer would be correct if

The registrar required manual authoritative name server IP glue records rather than DNSSEC cryptographic delegation.

View source documentation

Last updated August 28, 2026Validated August 28, 2026

DNSSEC Chain of Trust and Zero Downtime KSK Rotation

Explanations

Create a Cloud DNS private peering zone linked to an external resolver, configure DNSSEC validation rules within the producer VPC, and submit the generated DNSSEC certificate to the registrar via TLS.

What this option proposes

Why it doesn't meet the requirement

Key limitations

This answer would be correct if

Enable DNSSEC on the Cloud DNS managed zone, retrieve the generated Delegation Signer (DS) record data, submit the DS record to the domain registrar, and when rotating the KSK, add the new KSK, publish the new DS record at the registrar, wait for the DS TTL to expire, and then delete the old KSK.

What DNSSEC in Cloud DNS is

How it meets the requirements

Key advantages

Why this is optimal

Enable DNSSEC on the Cloud DNS managed zone, immediately delete the default KSK to generate a new key pair, upload the new public key directly to Cloud DNS response policies, and leave registrar DS configurations blank.

What this option proposes

Why it doesn't meet the requirement

Key limitations

This answer would be correct if

Enable DNSSEC on the Cloud DNS managed zone, export the Zone Signing Key (ZSK) public key string, add the raw ZSK as an NS record at the registrar, and rotate the ZSK every 30 days by modifying registrar settings.

What this option proposes

Why it doesn't meet the requirement

Key limitations

This answer would be correct if

Try 10 interactive questions like this one, free

Related questions

Cloud DNS Peering with Response Policies

Cloud DNS Server Policies and Query Logging

Cloud Logging Sinks to Chronicle UDM

On-Demand Scanning Pre-Push Gating

Cloud DLP FPE with KMS Wrapped Keys

IAM Policy Intelligence for Least Privilege

DNSSEC Chain of Trust and Zero Downtime KSK Rotation

Explanations

Create a Cloud DNS private peering zone linked to an external resolver, configure DNSSEC validation rules within the producer VPC, and submit the generated DNSSEC certificate to the registrar via TLS.

What this option proposes

Why it doesn't meet the requirement

Key limitations

This answer would be correct if

Enable DNSSEC on the Cloud DNS managed zone, retrieve the generated Delegation Signer (DS) record data, submit the DS record to the domain registrar, and when rotating the KSK, add the new KSK, publish the new DS record at the registrar, wait for the DS TTL to expire, and then delete the old KSK.

What DNSSEC in Cloud DNS is

How it meets the requirements

Key advantages

Why this is optimal

Enable DNSSEC on the Cloud DNS managed zone, immediately delete the default KSK to generate a new key pair, upload the new public key directly to Cloud DNS response policies, and leave registrar DS configurations blank.

What this option proposes

Why it doesn't meet the requirement

Key limitations

This answer would be correct if

Enable DNSSEC on the Cloud DNS managed zone, export the Zone Signing Key (ZSK) public key string, add the raw ZSK as an NS record at the registrar, and rotate the ZSK every 30 days by modifying registrar settings.

What this option proposes

Why it doesn't meet the requirement

Key limitations

This answer would be correct if

Try 10 interactive questions like this one, free

Related questions

Cloud DNS Peering with Response Policies

Cloud DNS Server Policies and Query Logging

Cloud Logging Sinks to Chronicle UDM

On-Demand Scanning Pre-Push Gating

Cloud DLP FPE with KMS Wrapped Keys

IAM Policy Intelligence for Least Privilege