SD-WAN-Engineer Exam Dumps - Paloalto Networks Network Security Administrator Questions and Answers

Comprehensive and Detailed Explanation

According to Palo Alto Networks Prisma SD-WAN administrator documentation regarding Path Policy configuration, specific rules apply when utilizing Standard VPNs (IPSec tunnels to non-ION devices, such as Prisma Access or third-party firewalls) as an L3 Failure Path.

When a Path Policy rule is configured, the administrator defines Active Paths, Backup Paths, and L3 Failure Paths. The L3 Failure Path is a "last resort" mechanism used when all Active and Backup paths are unavailable (Layer 3 down).

If Standard VPN is selected as the L3 Failure Path type, the system explicitly requires that the administrator also associates it with a specific Standard Services and DC Group within that same policy rule.

The ION device uses the Standard Services and DC Group to identify the specific remote endpoint (tunnel destination) where the traffic should be routed. Unlike a "Direct" (Internet) path which can simply route out to the WAN, a Standard VPN represents a logical tunnel. If the policy rule designates "Standard VPN" as the failure path but leaves the "Standard Services and DC Group" field empty or unselected, the ION effectively has a directive to "use a VPN" but lacks the instruction on which VPN group to use for this specific application context. Consequently, even if the IPSec tunnel to Prisma Access is physically up and stable, the policy engine cannot resolve the next hop for the "SuperSaaSApp" traffic, resulting in the packets being dropped. To resolve this, the administrator must edit the Path Policy rule to ensure the specific Standard Service/DC Group representing Prisma Access is checked/selected for the L3 Failure Path.

Palo Alto Networks utilizes an aggregate throughput model for Prisma SD-WAN licensing.1 The minimum bandwidth subscription required for a branch ION is determined by the maximum traffic (the sum of both ingress and egress) that passes through the ION device. This is often referred to as "Aggregate Throughput." It is a critical distinction in the Prisma SD-WAN architecture because the license must account for all traffic processed by the device, whether that traffic stays local (Direct Internet Access), goes to the Data Center via the VPN fabric, or moves between local LAN segments.

When sizing a subscription, engineers must evaluate the total capacity of the WAN circuits connected to the branch. For example, if a branch has two 100 Mbps internet circuits, the device is capable of processing 200 Mbps of egress traffic and 200 Mbps of ingress traffic simultaneously. However, the licensing is based on the aggregate peak throughput the customer expects to utilize across the device's interfaces.

Choosing an under-sized subscription based only on "fabric traffic" (Option B) or "ISP capacity" (Option D) without considering the total bi-directional flow can lead to artificial performance bottlenecks. If the traffic exceeds the licensed bandwidth, the ION device will police the traffic to the licensed limit, regardless of the physical port speed or the hardware's theoretical maximum. Therefore, the subscription must be aligned with the total actual traffic volume the device is expected to handle to ensure an optimal user experience and full utilization of available circuit bandwidth.

In Prisma SD-WAN, path selection and traffic symmetry are governed by the Path Policy and the available physical/virtual circuits at a site. The scenario describes a situation where return traffic is dropped on the branch ION after arriving via an Internet overlay. To understand why, we must analyze the "Active" and "Backup" paths defined in the policy.

The policy specifies Active = MPLS Overlay and Backup = Prisma Access on internet. In a healthy environment, the ION device expects to send and receive traffic based on these defined paths. If the site actually has two internet circuits and no MPLS circuit (Option C), a critical mismatch occurs. Because there is no MPLS circuit available to satisfy the "Active" path, the device will fall back to the "Backup" path for initiated traffic.

However, the core issue here relates to how Prisma SD-WAN handles asymmetric routing and session state. If traffic arrives at the branch via an "Internet Overlay" path that is not explicitly defined or allowed as a valid path for that specific application in the Path Policy, the ION device's flow integrity checks may drop the packets. Specifically, if the ION is configured with only Internet circuits but the policy is looking for an MPLS overlay that doesn't exist, the device may fail to correctly associate the return packets with the session state if the paths are perceived as "unbound" or "invalid" per the policy. This behavior is a security feature designed to ensure that traffic only traverses paths that meet the administrator's defined performance and security criteria. Without an MPLS circuit present, the policy cannot be fully realized, leading to potential drops for traffic arriving on paths not intended for that specific application flow.

In Prisma SD-WAN, Performance Policies are the primary mechanism used to define the expected quality of experience for specific applications. Unlike traditional monitoring that relies solely on "up/down" interface states, Prisma SD-WAN focuses on the actual health of the application path. An incident is triggered when the system detects a violation of defined service-level agreement (SLA) thresholds, such as excessive latency, jitter, or packet loss, even if the physical link remains active.

When an administrator configures a performance policy, they set specific bounds for these metrics. For example, a VoIP application might have an SLA requiring latency below 150ms and packet loss below 1%. If the ION device detects that the current path (e.g., a broadband circuit) exceeds these limits, it generates a performance incident. This incident serves two purposes: first, it alerts the administrator to the degradation; second, it triggers the Path Selection engine to proactively steer the application traffic to a more suitable "Backup" or "Available" path that currently meets the SLA requirements.

Options B, C, and D represent system-level or network-level events that generate different types of alerts or incidents (System or Network incidents), but they are not the triggers defined within a Performance Policy. Performance policies are specifically concerned with the application's perceived performance across the fabric. By focusing on SLA violations rather than just physical link status, Prisma SD-WAN ensures that business-critical applications remain functional even during "brownout" conditions where a circuit is technically "up" but performing poorly.

Comprehensive and Detailed Explanation

In Prisma SD-WAN Path Policies, the Service & DC Group (Destination) field determines where the traffic is sent.

Direct: This is the specific keyword/object used to instruct the ION to route traffic directly out to the local WAN interface (Local Breakout) towards the Internet, without encapsulation in a VPN tunnel. This is the correct setting for Guest Wi-Fi, SaaS applications (like Office 365), or any public web browsing that does not need to be backhauled.

Standard VPN / Default-Cluster: These options direct traffic into an IPSec overlay tunnel destined for a Data Center or another ION. Selecting these would "backhaul" the guest traffic, which contradicts the requirement for DIA.

When "Direct" is selected, the ION uses its available "Internet" category links. The policy can further specify which internet link to use (e.g., "Use Broadband, avoid LTE") via the path preference list, but the Destination type must be "Direct".

Prisma SD-WAN licensing is structured to provide flexibility while ensuring that all components of the secure fabric are correctly accounted for. To meet the requirements of this organization, we must calculate the necessary subscriptions for both the data center hubs and the distributed branch network.

First, we address the Data Center Subscriptions. The organization has two main geographically separate data centers and one small data center, all of which require High Availability (HA). In a Prisma SD-WAN deployment, HA at a site is achieved by deploying two ION devices in a cluster. Palo Alto Networks licensing requires a separate Data Center subscription for each ION device acting as a hub. Therefore, with three data center locations (2 main + 1 small) each requiring an HA pair (2 devices per site), a total of six data center subscriptions (Option A) are required to license all six hub appliances.

Second, we address the Branch Subscriptions. The organization has 50 branches but lacks accurate measurements of actual bandwidth consumption. Palo Alto Networks' best practice for such scenarios is the Aggregate Bandwidth Subscription model (Option B). Instead of purchasing a fixed "Branch subscription per site" (Option D)—which requires knowing the exact throughput needs for every individual location—the aggregate model allows the customer to purchase a total pool of bandwidth (e.g., 5 Gbps) that is shared across all 50 branch sites.

This "pay-as-you-grow" approach is ideal when consumption patterns are unknown or inconsistent. As branches utilize the bandwidth, it is deducted from the central pool. This avoids the risk of over-provisioning licenses at low-usage sites or under-provisioning at high-usage sites. Together, the six DC subscriptions and the aggregate bandwidth pool provide a fully licensed, HA-capable SD-WAN environment that aligns with Palo Alto Networks' scaling recommendations.

Comprehensive and Detailed Explanation

Prisma Access manages Remote Network bandwidth using an Aggregate Bandwidth licensing model.

Compute Locations: When you purchase bandwidth (e.g., 1 Gbps), you allocate it to specific Prisma Access Compute Locations (e.g., US West, Europe Central).

Shared Pool: All branch sites (Remote Networks) that connect to that specific Compute Location share the allocated bandwidth pool. For example, if you allocate 500 Mbps to "US West" and connect 10 branches to it, they compete for that 500 Mbps aggregate.

Bursting: An individual branch is not strictly rate-limited to a "slice" (e.g., 50 Mbps) unless you explicitly configure QoS guarantees. By default, a single branch can burst and consume a large portion of the aggregate pool if other branches are idle. The enforcement happens at the Region/Compute Node level, ensuring the total throughput does not exceed the licensed capacity for that region.

Comprehensive and Detailed Explanation

In Prisma SD-WAN, Custom Applications are global policy objects managed centrally on the controller.

Immediate Propagation: When an administrator creates or modifies a Custom Application definition (e.g., updating the IP subnet or port for an internal app), the Prisma SD-WAN controller automatically pushes this update to all connected ION devices in the tenant.

No Manual Push: Unlike some legacy firewall management paradigms (like Panorama "Commit and Push"), the Prisma SD-WAN architecture is "intent-based" and continuously synchronized. A change to a global object like an App Definition is considered a live configuration change and is distributed immediately via the secure control channel.

No Reboot: The ION data plane updates its classification engine dynamically without interrupting traffic or requiring a reboot. This ensures that policy enforcement (steering "Inventory_App" to the correct path) remains accurate in real-time.

Comprehensive and Detailed Explanation

In the Prisma SD-WAN Flow Browser, the Flow State provides a real-time snapshot of the TCP/UDP session lifecycle.

INIT (Initialization): This state indicates that the ION device has seen the initial packet of a new session (typically a TCP SYN) originating from the client (Source), but it has not yet seen a return packet (such as a TCP SYN-ACK) from the destination server.

Diagnosis: A flow stuck in INIT is a classic indicator of a "Blackhole" or reachability issue downstream. It implies that the ION successfully routed the packet out toward the destination, but the destination did not reply. Common causes include:

The server is offline.

A firewall in the path (or on the server itself) is dropping the traffic.

Routing is broken on the return path (asymmetric routing where the return traffic bypasses the ION).

If the flow had been denied by the ION's own firewall (Option C), the state would typically show as DENY or REJECT. If the handshake completed (Option A), the state would be ESTABLISHED. Therefore, INIT points to a lack of response from the remote end.

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.