How does virtualization contribute to network architecture?

Virtualization significantly contributes to network architecture primarily by enabling multiple virtual machines to operate on a single physical server. This process allows for improved resource utilization as it maximizes the capabilities of available hardware. By consolidating workloads, organizations can reduce the number of physical servers needed, which in turn decreases power consumption, cooling requirements, and overall physical space needed for infrastructure.

Furthermore, virtualization enhances flexibility and scalability within network environments. Virtual machines can be easily created, modified, and deleted according to workload demands, allowing businesses to respond more effectively to changing needs. This approach also simplifies management tasks and can lead to more streamlined disaster recovery processes due to the ease with which virtual machines can be backed up and replicated.

The other options do not accurately represent the primary benefits or roles of virtualization in network architecture. For instance, restricting the number of servers in use does not capture the overall aim of virtualization, which is to optimize the existing hardware, nor does isolating all network traffic directly pertain to virtualization's core benefits. Increasing physical hardware requirements is contrary to the cost-saving and efficiency objectives that virtualization typically seeks to achieve.