What are "Custom Applications" used for in Palo Alto Networks firewalls?

Custom Applications in Palo Alto Networks firewalls are utilized to define applications that are not recognized by the standard App-ID feature. App-ID is a crucial technology that identifies applications based on various characteristics rather than just port or protocol. However, there are instances in which certain applications might not be identified by the predefined App-ID signatures.

Creating Custom Applications allows organizations to extend the built-in capabilities of their firewalls by specifying characteristics such as ports, protocols, and other parameters that sufficiently describe the application. This ensures that unrecognized applications can still be effectively managed and monitored, enhancing security posture and traffic policies within the network.

The other options do not accurately represent the purpose of Custom Applications: deleting unwanted applications is a different process, restricting access relates more to policy enforcement rather than identification, and scheduling application updates pertains to maintenance rather than the definition or recognition of applications.