Paloalto Networks SD-WAN-Engineer Dumps Questions Answers

Comprehensive and Detailed Explanation

Prisma SD-WAN supports Dynamic VPNs (Branch-to-Branch) even when both endpoints are behind Source NAT (e.g., typical broadband connections).

To achieve this, the ION devices utilize standard NAT Traversal techniques, specifically leveraging STUN (Session Traversal Utilities for NAT).

Discovery: Each ION communicates with the Cloud Controller (which acts as a STUN server/signaling broker). Through this communication, the controller observes the public IP and Port that the ION's traffic is coming from (the post-NAT address).

Signaling: The controller shares this public reachability information with the peer ION.

Hole Punching: The IONs then attempt to initiate connections to each other's discovered public IP/Port. This "UDP Hole Punching" allows them to establish a direct IPSec tunnel through the NAT devices without requiring static 1:1 NAT mapping or manual port forwarding on the provider routers, enabling mesh connectivity in commodity internet environments.

Comprehensive and Detailed Explanation

The Flow Browser and App Response Time metrics in Prisma SD-WAN are critical tools for isolating the fault domain—determining whether a problem lies in the "Network" or the "Application."

Network Transfer Time (NTT) / Round Trip Time (RTT): These metrics measure the time it takes for packets to traverse the network (WAN/LAN) and for acknowledgments to return. A low NTT (e.g., <50ms) confirms that the network pipes (SD-WAN overlay, Underlay circuits) are healthy and transporting packets quickly.

Server Response Time (SRT): This metric specifically measures the time between the server receiving a request and the server sending the first byte of the response. It essentially measures the "processing time" of the backend server.

In the scenario described, the network metrics (NTT/RTT) are excellent, effectively ruling out WAN congestion, packet loss, or latency (Option A and C). However, the Server Response Time (SRT) is very high (500ms). This signature is a definitive indicator that the network delivered the request instantly, but the application server took a long time to process it. This points the troubleshooting effort toward the server infrastructure (e.g., a slow SQL query, an overloaded web server, or lack of compute resources) rather than the SD-WAN environment.

Comprehensive and Detailed Explanation

In a Prisma SD-WAN Data Center deployment, the operational state of the Secure Fabric VPNs (overlay tunnels) is directly tied to the health of the BGP Core Peer configuration.4

Core Peer Dependency: DC ION devices typically peer with the data center core switch (Core Router) via BGP to learn the subnets (prefixes) for the applications hosted in the DC. The Prisma SD-WAN controller monitors this BGP peering status.5

Controller Logic: If the BGP Core Peer on a DC ION goes down (or is not established), the controller automatically marks the VPN tunnels terminating at that specific ION as "Inactive".6 This is a fail-safe mechanism designed to prevent remote branches from sending traffic to a DC ION that has lost conne7ctivity to the internal data center network (and thus the applications).

Scenario Analysis: In this scenario, DC ION-1 has active VPNs, meaning its BGP Core Peer is UP and it is successfully advertising reachability. DC ION-2 has no active VPNs, which strongly indicates that its BGP Core Peer is down.8 Because the controller sees the peer is down, it suppresses the tunnel establishment or marks existing tunnels as inactive to ensure traffic is only directed to the healthy node (ION-1).