Your network contains two Active Directory Domain Services (AD DS) forests named contoso.

Modify the trust on : DC2

Modify the permissions for the : Computer object of SRV1

In an Active Directory Domain Services (AD DS) environment involving multiple forests and external trusts, managing granular access across domain boundaries is achieved through Selective Authentication . According to official documents for Administering Windows Server Hybrid Core Infrastructure, there are two primary authentication settings for a trust: Domain-wide authentication and Se lective authentication .

When you need to restrict users from a trusted forest (contoso.com) so they can only access specific resources in the trusting forest (adatum.com), you must configure the trust to use Selective Authentication . This configuration must be performed in the resource domain (the trusting domain). Based on the provided table, DC2 is the domain controller for adatum.com , which is where the shared resources (SRV1) reside. Therefore, you must modify the trust properties on DC2 to enable Selective Authentication for the incoming trust from contoso.com.

Once Selective Authentication is enabled, Windows does not automatically grant the " Authenticated Users " SID to the user ' s access token for resources in the local domain. Instead, administrators must explicitly grant the Allowed to Authenticate permission on the specific resource ' s computer object. In this scenario, since the requirement is to restrict access specifically to resources on SRV1 , you must modify the security permissions on the Comput er object of SRV1 in Active Directory Users and Computers. By granting the contoso.com users (or a group containing them) this permission, they can successfully authenticate against SRV1 while being blocked from all other servers in the adatum.com forest. This satisfies the requirement to prevent access to any other resources while maintaining the ability of adatum.com users to access contoso.com (as the 2-way trust remains intact).