What is a distributed switch in VMware used for?

A distributed switch in VMware is primarily used for centralized management of virtual networking across multiple ESXi hosts. This capability enables administrators to manage the virtual networking configuration in a consistent manner across the entire datacenter, rather than configuring each host individually. By using a distributed switch, network resources such as port groups, network policies, and uplinks can be defined at the datacenter level, simplifying management and enhancing operational efficiency.

This approach is particularly beneficial in environments where there are numerous virtual machines (VMs) and host servers, as it provides a scalable and streamlined method to implement network policies and configurations. Changes made on the distributed switch are automatically propagated to all the ESXi hosts that are connected to it, which eliminates the repetitive task of configuring each host separately, minimizes the chances of misconfigurations, and enhances network reliability and performance.

In contrast, the other options do not align with the primary function of distributed switches. Centralized management of physical switches, for example, pertains more to physical network infrastructure rather than virtual network management. Isolated networks for VM testing are typically facilitated by other virtual networking features like port groups or private VLANs but do not utilize the distributed switch as the primary tool. Lastly, establishing a high-speed connection between storage and VM is more