Comprehensive and Detailed In-Depth Step-by-Step Explanation:Increasing throughput for a VM-Series firewall running on VMware ESXi with flexible licensing requires adjusting virtual CPU (vCPU) resources, which impacts performance tiers. The Palo Alto Networks Systems Engineer Professional - Software Firewall documentation outlines the process for modifying VM-Series resources to minimize downtime, particularly for flexible-license models.

Option B (Correct Answer): This order minimizes downtime by ensuring all steps are performed efficiently and safely:

Power-off the VM and increase the vCPUs within the hypervisor: Shutting down the VM-Series firewall on ESXi avoids any risk of corruption or performance issues during resource changes. Increasing vCPUs in the hypervisor (e.g., VMware vSphere) adjusts the hardware resources allocated to the VM, enabling higher throughput.

Increase the vCPU within the deployment profile: After adjusting the hypervisor, update the deployment profile in the Palo Alto Networks Customer Support Portal or Strata Cloud Manager to reflect the new vCPU count, ensuring the flexible license aligns with the updated resources.

Retrieve or fetch license keys on the VM-Series NGFW: With the vCPU change applied, the VM-Series fetches or retrieves new license keys based on the updated deployment profile, activating the higher-tier performance level (e.g., from Tier 1 to Tier 2).

Confirm the correct tier level and vCPU appear on the NGFW dashboard: After powering on and licensing, verify the VM-Series dashboard shows the updated vCPU count and corresponding performance tier, ensuring throughput increases as expected.

Power-on the VM-Series NGFW: Restart the VM to apply changes, minimizing downtime by ensuring all preparatory steps (power-off, resource adjustment, licensing) are completed before rebooting.This sequence minimizes downtime by handling resource changes offline, updating licensing, and validating the configuration before bringing the firewall back online, as recommended in the documentation for flexible licensing and VM resource adjustments.

Options A, C, and D are incorrect because they involve powering off the VM after licensing or resource changes, increasing downtime or risking configuration errors. For example, Option A powers off after increasing vCPUs in the profile and licensing, delaying the physical resource adjustment. Option C powers off after licensing, potentially causing licensing mismatches. Option D powers on the VM before licensing and profile updates, risking operational issues or downtime during reconfiguration. The documentation emphasizes minimizing downtime by completing all preparatory steps before rebooting, making Option B the optimal sequence.

References: Palo Alto Networks Systems Engineer Professional - Software Firewall, Section: VM-Series Flexible Licensing, VMware ESXi Deployment Guide, Performance Tuning and Resource Adjustment Documentation.