The Administering Windows Server Hybrid Core Infrastructure materials state the placement and provisioning requirements for IP Address Management (IPAM). Specifically:

“The IPAM server must be installed on a domain member computer . You cannot install the IPAM server feature on a domain controller .”

“IPAM manages and discovers domain controllers, DHCP servers, and DNS servers in the domain. Servers in a workgroup are not supported as managed servers.”

“When you choose Group Policy–based provisioning , IPAM creates and links GPOs that configure the required settings on managed DC/DHCP/DNS servers so that IPAM can perform inventory, event collection, and address space management.”

Applying these rules:

Server2 is a domain-joined Windows Server Core member with no conflicting roles, satisfying the guidance to avoid installing IPAM on a DC and aligning with the recommendation to place IPAM on a dedicated member server. DC1 is a domain controller (and DNS), so it must not host IPAM. Server1 (DHCP) could host IPAM but best practice is to use a dedicated server. Server3 is in a workgroup, so it cannot host IPAM or be managed by it.

For GPO-based provisioning and server discovery, the managed servers that must be provisioned are the infrastructure role holders: DC1 (AD DS/DNS) and Server1 (DHCP). These are exactly the servers IPAM discovers and manages via the created GPOs.