Paloalto Networks SD-WAN-Engineer Exam With Confidence Using Practice Dumps

Comprehensive and Detailed Explanation

The stability of VPN tunnels in the Prisma SD-WAN + Prisma Access integration relies on standard IPSec mechanisms.

Dead Peer Detection (DPD): The CloudBlade configuration automatically enables DPD on the IPSec tunnels it provisions.

Mechanism: DPD is a standard keepalive mechanism where the ION device sends periodic "R-U-THERE" messages to the Prisma Access gateway (and vice versa). If no acknowledgment is received after a specific count/timer, the ION marks the tunnel as down and attempts to re-key or switch to a backup path.

Synthetic Probes (B): While Synthetic Probes (part of ADEM or Path Quality monitoring) can be configured to measure latency/loss, the fundamental mechanism that keeps the IPSec security association (SA) active and detects link failure is DPD, not an application-layer probe.

Comprehensive and Detailed Explanation

The Self-Zone is a predefined security zone in the Prisma SD-WAN ZBFW that represents the ION device's own control plane and management traffic.

Default Rule: The security policy contains an implicit, uneditable default rule that Allows traffic originating from the Self-Zone to any destination zone (Internet, Private WAN, etc.).

Rationale: This ensures that the device can always perform essential critical functions—such as connecting to the Cloud Controller, resolving DNS, syncing time via NTP, and establishing VPN tunnels—without the administrator needing to manually create "Allow" rules for the device itself. If this traffic were blocked by a "Deny All" default, the device would become unmanageable (bricked) immediately after applying the policy.

Comprehensive and Detailed Explanation

The AppX (Application Experience) score is a proprietary metric used by Prisma SD-WAN to provide a holistic view of user experience, rather than just network statistics. It is calculated based on three key components:

Transaction Failure Rate (A): The percentage of application transactions that failed (e.g., TCP resets, HTTP 500 errors). This indicates availability.

Network Transfer Time (B): The time taken for packets to traverse the network (WAN/LAN latency). This indicates network health.

Server Response Time (C): The time taken by the application server to respond to a request. This indicates backend performance.

Why not D or E?

Bandwidth Utilization (D) is a capacity metric, not a direct measure of quality. A link can be 90% full but still deliver packets quickly (good AppX), or 10% full but dropping packets (bad AppX).

Jitter (E) is a network-layer metric primarily relevant for UDP Real-Time media. While important, the high-level "AppX" score for general TCP apps focuses on the "Time-to-Glass" metrics (NTT/SRT) and success rates.