What primary action is performed at the beginning of creating a shortcut trust?

The primary action performed at the beginning of creating a shortcut trust is to select "New Trust" from the Trusts tab. This action represents the initial step in the trust setup process within the Active Directory. By initiating a new trust, you begin the defined procedure to establish a trust relationship between two domains that may be located in different Active Directory forests or between domains within the same forest.

Once the "New Trust" action is selected, you are guided through a series of steps to input necessary details such as the type of trust, domain names, and trust direction. This initial selection is crucial as it sets the foundation for the configuration of the trust, allowing administrators to streamline authentication across different domains.

While considering the other options, accessing the Domain Controller properties involves managing specific configurations but is not the first step in establishing a trust. Identifying the source domain is an important aspect, but it comes into play after the trust creation process has begun, not at the very start. Determining replication needs is related to ensuring that domain data synchronizes appropriately but does not pertain directly to the creation of a trust itself. Thus, selecting "New Trust" accurately reflects the correct initial action in establishing a shortcut trust between domains.