What can be applied to prevent users from unknowingly downloading malicious file types from the internet?

XYZ Corporation has a legacy environment with asymmetric routing. The customer understands that Palo Alto Networks firewalls can support asymmetric routing with redundancy.
Which two features must be enabled to meet the customer's requirements? (Choose two.)

Palo Alto Networks publishes updated Command-and-Control signatures. How frequently should the related signatures schedule be set?

A customer requests that a known spyware threat signature be triggered based on a rate of occurrence, for example, 10 hits in 5 seconds.
How is this goal accomplished?