Which firewall, if any, supports only a single power supply?

The option stating that none of the firewalls support only a single power supply is correct, as it highlights the typical design philosophy in enterprise-grade firewall systems. Redundancy in power supply is a critical feature for maintaining high availability and minimizing downtime in data centers.

Firewalls like the PA-220, PA-850, and PA-7050 are designed with this redundancy in mind. These devices often include dual power supply units, allowing them to operate even if one power source fails. This is essential in critical environments where a constant network presence is necessary for operations.

In situations where power supply failure can lead to significant impacts, organizations prefer devices that offer built-in redundancy. This not only enhances reliability but also supports the overall uptime of systems dependent on these firewalls.