How can an administrator create a custom application signature in Palo Alto Networks?

Creating a custom application signature in Palo Alto Networks is accomplished effectively by using the App-ID tool. This tool allows administrators to define unique application attributes such as the application’s behavior, traffic characteristics, and protocol specifics.

Using the App-ID tool, an administrator can analyze traffic patterns and create a detailed profile for the application. This ensures that the application signature accurately represents the application's distinctive characteristics in terms of how it communicates over the network, enabling more precise identification and control of applications in your security policies.

The other options do not align with best practices for creating custom application signatures. Modifying existing settings directly could lead to potential conflicts with existing signatures. Solely relying on CLI commands can be limiting and may not offer the intuitive capabilities of the App-ID tool. Meanwhile, submitting a request to support is not a proactive method of signature creation and relies on an external response rather than empowering the administrator to manage their own application identification needs.