Description

Cloud DNS logging records the queries from the name servers within your VPC to Stackdriver. Logged queries can come from Compute Engine VMs, GKE containers, or other GCP resources provisioned within the VPC.

Default value

Cloud DNS logging is disabled by default on each network.

Rationale

Security monitoring and forensics cannot depend solely on IP addresses from VPC flow logs, especially when considering the dynamic IP usage of cloud resources, HTTP virtual host routing, and other technology that can obscure the DNS name used by a client from the IP address. Monitoring Cloud DNS logs provides visibility into DNS names requested by the clients within the VPC. These logs can be monitored for anomalous domain names and evaluated against threat intelligence.

To fully capture DNS logging records, your firewall must block egress for UDP/53 (DNS) and TCP/443 (DNS over HTTPS) to prevent the client from using an external DNS name server for resolution.

Only queries that reach a name server are logged. Cloud DNS resolvers cache responses, queries answered from caches, and direct queries to an external DNS resolver outside the VPC are not logged.

Impact

Enabling of Cloud DNS logging might result in your project being charged for the additional logs usage.

Remediation

From the command line

For VPC networks that need a new DNS policy with logging enabled, run the following:

gcloud dns policies create enable-dns-logging --enable-logging --
description="Enable DNS Logging" --networks=VPC_NETWORK_NAME

The VPC_NETWORK_NAME can be one or more networks in a comma-separated list. For VPC networks that have existing DNS policies, run the following to enable logging:

gcloud dns policies update POLICY_NAME --enable-logging --
networks=VPC_NETWORK_NAME

The VPC_NETWORK_NAME can be one or more networks in a comma-separated list.

References

1. https://cloud.google.com/dns/docs/monitoring