SD-WAN-Engineer Practice Questions

Comprehensive and Detailed Explanation

Site Templates (often referred to as Site Configuration Templates) are a critical tool for the Zero Touch Provisioning (ZTP) of large-scale deployments in Prisma SD-WAN.

1. Device Pre-staging (Statement C):

One of the primary capabilities of Site Templates is the creation of Device Shells. A device shell is a configuration container that exists in the controller before the physical hardware is installed or connected. By using a template, an administrator can pre-provision the entire configuration (interfaces, routing, subnets) for the "Site" and "Element" (Device). When the physical ION device is later connected to the internet and claimed (associated with the shell via its Serial Number), it immediately inherits this pre-staged configuration, enabling a true "plug-and-play" deployment.

2. Mandatory Variables (Statement B):

To successfully instantiate a functional site from a generic template, specific unique identifiers are required in the variable data set (typically a CSV file).

Site Name: Identifies the location in the portal.

ION Software Version: Ensures the device boots to the specific validated code version required for the deployment, preventing inconsistencies.

ION Serial Number / Device Name: Required to bind the logical configuration (Shell) to the physical hardware. Even if the serial is added later during the claim process, the structure of the template and the deployment workflow mandates these variables to ensure the device can be uniquely identified and managed within the fabric.

Note on Option D: While it is technically possible to re-deploy a template, the Best Practice for "Day 2" operations (updating or modifying configuration after deployment) is to use Prisma SD-WAN Stacks (Network Stacks, Security Stacks, etc.). Stacks allow for granular, policy-based updates across multiple sites without the destructive or rigid nature of re-applying a full site initialization template. Therefore, D is not the aligned best practice.

Comprehensive and Detailed Explanation

Prisma SD-WAN calculates the Mean Opinion Score (MOS) to provide a standardized metric (1-5) for voice quality. To ensure the system always knows the "voice readiness" of a path—even before a call starts—it uses Active Probes (synthetic UDP packets).

While latency is measured, the MOS calculation algorithm is most heavily penalized by Packet Loss (D) and Jitter (B).

Packet Loss: Even a small amount of loss (e.g., >1%) dramatically reduces voice clarity, causing dropouts.

Jitter: High variance in packet arrival time (jitter) causes the "robotic" voice effect and buffer underruns.

The system continuously measures these specific metrics on all WAN links using synthetic probes. If the packet loss or jitter exceeds the threshold defined in the "Path Quality Profile" (e.g., Voice Profile), the path is marked as non-compliant, and the MOS score drops, triggering a policy action to move the flow. Throughput (C) is less critical for voice as calls consume very little bandwidth (e.g., 64-100 Kbps), making congestion (loss/jitter) the primary enemy, not raw speed.

Comprehensive and Detailed Explanation

Prisma SD-WAN (formerly CloudGenix) integrates with Palo Alto Networks IoT Security to provide comprehensive visibility into all devices at a branch, including those that are not directly connected to the ION device. While the ION automatically detects and classifies devices connected directly to its interfaces via traffic inspection (DPI), DHCP, and ARP analysis, gaining visibility into off-branch devices (devices connected to downstream switches or access points) requires additional discovery mechanisms that can query the network infrastructure or ingest its logs.

1. SNMP (Simple Network Management Protocol): This is the primary active discovery method for off-branch devices. The Prisma SD-WAN ION device acts as a sensor that actively polls local network switches and wireless controllers using SNMP. By querying the ARP tables and MAC address tables (Bridge MIBs) of these intermediate network devices, the ION can identify endpoints that are connected to the switch ports, even if those endpoints are not currently sending traffic through the ION. This allows the system to map the topology and discover silent or lateral-traffic-only devices.

2. Syslog: In conjunction with SNMP, the IoT Security solution can utilize Syslog messages to discover and profile devices. Network infrastructure devices (like switches and WLAN controllers) can be configured to send Syslog messages to the collection point (which enables the IoT Security service) whenever a device connects or disconnects (e.g., port up/down events, DHCP snooping logs, or 802.1x authentication logs). These logs provide real-time data about device presence and identity (MAC/IP mappings) for devices that are not directly adjacent to the ION, ensuring 100% visibility across the branch network segments. LLDP (A) and CDP (B) are typically Link Layer discovery protocols used for discovering directly connected neighbors and do not propagate beyond the immediate link, making them unsuitable for discovering devices multiple hops away or behind a switch.

Prisma SD-WAN simplifies the integration with Prisma Access through a feature known as "CloudBlades," specifically the Prisma Access for Networks CloudBlade. The "easy onboarding" workflow is designed to automate the complex task of establishing secure tunnels between Branch ION devices and the SASE security processing nodes (SPNs).

When an administrator initiates this process, the system abstracts the manual configuration of IKE and IPSec parameters. Instead of manually defining an IPSec Crypto Profile or an IKE Profile (which are automatically handled by the CloudBlade orchestration), the user must specify where the traffic is going and which physical resources will handle the connection. The Prisma Access Primary Location (Option B) is a mandatory selection because it determines the geographical region and specific compute instance within the Prisma Access cloud that will serve as the primary security gateway for that branch.

Furthermore, the IPSec Termination Node (Option D) must be selected to define the specific endpoint within the Prisma Access infrastructure where the ION device's tunnels will terminate. This selection ensures that the Controller can properly orchestrate the site-to-site VPN tunnels, ensuring that the branch traffic is correctly routed to the SASE fabric for security inspection. By selecting these two options, the CloudBlade can automatically negotiate the rest of the tunnel parameters, significantly reducing the potential for human error and accelerating the deployment of a Secure Access Service Edge (SASE) architecture across multiple branch locations.