Using Azure AD Domain Services with a personal host pool of five session hosts, you plan to add two new session hosts. What must you do before deploying the new hosts?

Before deploying new session hosts to an existing Azure Virtual Desktop host pool, you must generate a new registration key. This key is used during the host agent installation process on each new session host to securely register it with the specific host pool. Without a valid registration key, the new hosts cannot join the host pool and become available for user connections. Creating a scaling plan is for automatic scaling, not for manual host additions. Precreating a computer account in Azure AD DS is not a mandatory step for Azure Virtual Desktop session host deployment, as the host agent typically creates the account during the join process. Increasing the maximum session limit is a configuration setting for the host pool, not a prerequisite for adding new hosts.