Can Database Audit Be Used Across AZs?

Database audit is available only if the target database and your database audit instance are in the same region. If the database to be audited and the database audit instance you purchased are in different AZs in the same region, you can use database audit.

For example, if you have purchased database audit in AZ1 in a region, and the database to be audited is deployed in AZ2 or AZ3 in the region, you can use the database audit you purchased.