Data Access Management (DAM) policies are a feature of NDB Multi-Cluster that allows you to control the access and availability of time machine data across different Nutanix clusters. You can use DAM policies to specify which clusters can access the time machine data of a source database, and which clusters can replicate the time machine data for backup or disaster recovery purposes. DAM policies help you to optimize the storage and network resources, as well as ensure the security and compliance of your database workloads. The purpose of DAM policies is not to register multiple Nutanix clusters in NDB, as this is done by using the Add Cluster option in the NDB settings page. The purpose of DAM policies is also not to perform snapshot operations on a single Nutanix cluster, as this is done by using the Time Machine feature in the NDB dashboard. The purpose of DAM policies is also not to remove data accessibility of a time machine across all registered Nutanix clusters in NDB, as this is done by using the Delete option in the Time Machine page.
Reference: Nutanix Database Management & Automation Training Course, Module 6: Managing NDB Multi-Cluster, Lesson 2: Data Access Management Policies, Slide 3: Data Access Management Policies Nutanix Certified Professional - Database Automation (NCP-DB) 5 Exam, Section 6: Administer an NDB Environment, Objective 6.5: Apply procedural concepts to create Data Access Management (DAM) policies