Pass the Paloalto Networks Network Security Administrator SD-WAN-Engineer Questions and answers with Dumpstech

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 thepublicIP 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

In the Prisma SD-WAN (CloudGenix) Zero Touch Provisioning (ZTP) lifecycle, the device status transitions through specific stages that indicate its readiness and connectivity.

When an administrator enters the Claim Code (or Serial Number/Claim Code pair) into the portal, the device status immediately updates to "Claimed".

This status confirms that the portal has registered the device's unique identity and associated it with the customer's tenant. However, "Claimed" does not necessarily mean the device is fully operational or passing traffic yet. It simply signifies that the ownership is verified.

Once the physical device at the site successfully connects to the internet and reaches the Prisma SD-WAN Controller (using the call-home function), it will authenticate using its installed certificate. Upon successful authentication and the establishment of the secure control channel, the status will transition from "Claimed" to "Online".

Only after the device is "Online" can the controller push the specific site configuration (Device Shell), policies, and IP addressing required for the device to become "Provisioned" and eventually "Active" in the data path. If the device remains in the "Claimed" state for an extended period, it indicates that the hardware has not yet successfully contacted the controller, which prompts troubleshooting of the physical internet circuit or firewall rules upstream.

Comprehensive and Detailed Explanation

For a successful Zero Touch Provisioning (ZTP) experience, the ION device must be able to obtain an IP address and reach the internet immediately upon boot-up.

According to Palo Alto Networks hardware guides, the Controller Port (often labeled specifically as "CONTROLLER" on models like the ION 3000/7000/9000) is pre-configured to act as a DHCP client by default. It is the preferred interface for the initial "call home" process.

However, for smaller desktop models (like the ION 1000/2000/1200 series) or scenarios where a dedicated management network is not available, the device firmware is also configured to attempt DHCP client requests on Port 1 (often labeled as Internet 1 or simply 1).

Connecting the ISP circuit to any random port (like Port 4 or a LAN port) will not work for ZTP because those interfaces are not pre-configured as DHCP clients in the factory default state. Therefore, the installer must ensure the internet uplink is connected to either the dedicated Controller port or Port 1/Internet 1 to ensure the device can resolve the controller FQDN and download its configuration.

Comprehensive and Detailed Explanation

TheSITE_CONNECTIVITY_DOWNalarm is a high-severity alert indicating a total loss of overlay connectivity for a site.

It doesnottrigger if justonecircuit fails (Option B), provided that other circuits are still up and maintaining VPNs. A single link failure would typically trigger a "Link Down" or "VPN Down" alarm, but theSiteconnectivity would remain "Up" (degraded).

It does not simply mean the device rebooted (Option A), although a reboot would cause it temporarily; the alarm specifically tracks the state of the VPN fabric.

The SITE_CONNECTIVITY_DOWN alarm specifically generates when all Secure Fabric Links (VPN tunnels) on the device are in the "Down" state. This means the branch is completely isolated from the rest of the SD-WAN network (Data Centers and other branches), even if the device itself might still be powered on and reachable via the controller (management plane). It signifies a "Blackout" of the data plane for that location.

Comprehensive and Detailed Explanation

According to thePrisma SD-WAN Performance Policy Default Behaviordocumentation, the default action configured for applications (including real-time media) when a path experiences poor performance (violates the SLA thresholds for latency, jitter, or packet loss) is toMove Flows.

The Prisma SD-WAN ION device continuously monitors the health of all available paths. If the active path for a media application degrades and fails to meet the specified SLA, the default policy dictates that the traffic should be steered (moved) to an alternate, compliant path that meets the performance criteria.

WhileForward Error Correction (FEC)is a powerful feature available in Prisma SD-WAN to mitigate packet loss for real-time applications, it is anoptional actionthat must be explicitly enabled or configured within the performance policy rules. It is not thedefaultaction in the base system configuration; the primary default mechanism for handling performance issues is to leverage the multi-path fabric to switch to a better link.

Comprehensive and Detailed Explanation

In Prisma SD-WAN,Custom Applicationsare 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 toallconnected 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 Prisma SD-WAN (formerly CloudGenix), the establishment ofSecure Fabric(VPN) tunnels is automated but relies heavily on the correct definition of theNetwork Contextfor each interface. If a tunnel fails to form on a newly added s2econdary circuit, it is typically due to a misconfiguration in how the interface is defined in the ION portal.

1. Interface Scope (Statement D):

The Scope setting on an interface determines its function in the network topology.

Global Scope:This defines the interface as aWAN-facingport. The ION device will only attempt to build VPN tunnels (overlay) on interfaces configured with Global scope.

Local Scope:This defines the interface as aLAN-facingport (for users, switches, or APs). If the administrator mistakenly sets the scope to "Local" for the new internet line, the ION treats it as a private LAN segment and willnotinitiate any tunnel negotiation or WAN signaling on that port.

2. Interface Role/Circuit Category (Statement A):

Prisma SD-WAN uses Circuit Categories (often referred to as Interface Roles in general networking terms, or specifically "Circuit Category" in the ION UI) to determine peering logic.

To form a tunnel over a public internet link to a Data Center, the circuit attached to the interface must be categorized as"Internet".

The controller uses this category to match compatible endpoints. It knows that a "Private WAN" (MPLS) link cannot directly tunnel to an "Internet" link without a gateway. If the new circuit is not correctly selected/categorized as "Internet" (e.g., left undefined or set to a different category), the system will not attempt to build the standard IPSec overlay to the Data Center's public IP address.

Comprehensive and Detailed Explanation

In a Prisma SD-WAN Data Center deployment, the operational state of theSecure Fabric VPNs(overlay tunnels) is directly tied to the health of theBGP Core Peerconfiguration.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 theBGP Core Peeron a DC ION goes down (or is not established), the controller automatically marks the VPN tunnels terminating at that specific ION as"Inactive".6This 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 hasnoactive VPNs, which strongly indicates that itsBGP Core Peer is down.8Because 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).

Comprehensive and Detailed Explanation

The Prisma SD-WAN (CloudGenix) solution is designed with a separation of the control plane (Controller) and the data plane (ION devices).1In the event that an ION device loses connectivity to the Cloud Controller (often referred to as running in "headless mode"), the device continues to forward traffic and maintain existing VPN tunnels using the keys it currently holds.2

However, for security purposes, theVPN session keys(shared secrets) used for the Secure Fabric have a finite validity period. The system is designed such that these keys are rotated regularly.3If the controller is unreachable, the ION device can continue to rotate keys locally and maintain the VPNs for a maximum default period of72 hours(exactly3 days).4

If the connection to the controller is not restored within this 72-hour window, the keys will eventually expire, and the ION will be unable to retrieve new authorized key material from the controller.5Consequently, the VPN tunnels will go down, and the "out of shared secret key" error will be observed in the VPN status logs. This mechanism ensures that a permanently compromised or stolen device cannot maintain network access indefinitely without central authorization.

Comprehensive and Detailed Explanation

In a Prisma SD-WAN High Availability (HA) deployment, theHA Control Interfaceis the critical lifeline used to synchronize state, heartbeats, and flow information between the Active and Standby ION devices.

The strict requirement for this connection is that it must beLayer 2 adjacent.

Best Practice:A direct physical cable connection between the designated HA ports of the two devices (e.g., Port 2 on Device A to Port 2 on Device B).

Alternative:Connectivity through a switch on a dedicated, isolated VLAN is supported, provided the devices are in the same broadcast domain and subnet.

Routing (Layer 3) isnot supportedfor the HA Control link because the keepalive mechanism relies on low-latency, multicast/broadcast-level adjacency to detect failures instantly (sub-second failover). If the HA link were routed (Option A), network latency or router convergence issues could cause "Split-Brain" scenarios where both devices assume the Active role, leading to IP conflicts and traffic loops. Option C is incorrect because the Controller is too slow to manage real-time failover; the decision must be local.