Which component must have network access to all hosts it manages in VMware vSphere?

The vCenter Server is a critical component in VMware vSphere as it serves as a centralized management platform for all ESXi hosts and their virtual machines within a vSphere environment. It is responsible for tasks such as provisioning, monitoring, configuring, and managing the virtual infrastructure. For vCenter Server to effectively manage the ESXi hosts, it must have network access to each host. This access enables vCenter Server to send commands, retrieve status updates, and gather configuration details, ensuring coherent management across the entire virtual environment.

In contrast, the other components such as vCenter Single Sign-On, the Administration server, and the vSphere Web Client do not require direct network access to all managed hosts. vCenter Single Sign-On facilitates authentication for users accessing vSphere components but does not interact directly with each host for management purposes. The Administration server might handle administrative functions, while the vSphere Web Client provides a graphical interface for users and administrators but relies on the vCenter Server to perform actions on managed hosts. Hence, the requirement for network access to all hosts is specific to vCenter Server, making it the necessary component for management tasks.