B. The firewall evaluates the profiles in top-to-bottom order until one Authentication profile successfully authenticates the user.

Explanation:
When you configure Authentication Sequences on a Palo Alto firewall:
You first create individual Authentication Profiles (e.g., Kerberos, LDAP, TACACS+).
Then you create an Authentication Sequence, which lists those profiles in a top-to-bottom order.

During authentication:
The firewall checks the first profile in the list.
If it fails (e.g., user not found or authentication denied), it moves to the next profile in the sequence.
The process continues until one profile succeeds, or all fail.
📘 Reference:
Palo Alto Networks – Configure Authentication Sequences

❌ Why not the other options?
A. Alphabetical order
→ Incorrect. The order is explicitly defined by the admin in the Authentication Sequence, not by profile name.
C. Priority assigned
→ Incorrect. There is no numeric priority setting; the list order defines priority.
D. No further attempts if first times out
→ Incorrect. If the first method times out or fails, the firewall continues to the next profile in the sequence.

C. Create a custom application with specific timeouts, then create an application override rule and reference the custom application.

Explanation:
This solution is the fastest and most practical for internal applications with long idle periods and no threat inspection requirements. Here's why:

Custom Application with Timeouts:
You define a custom App-ID under Objects > Applications, setting extended session timeouts to accommodate idle behavior (e.g., hours without traffic). This prevents premature session termination.
Application Override Rule:
Under Policies > Application Override, you match traffic based on source/destination zone, IP, port, and protocol, then assign the custom App-ID. This bypasses Layer 7 inspection and ensures the firewall logs the traffic using your defined application name instead of unknown-tcp.

This method ensures:
Accurate logging for reporting
No threat scanning (as override disables Security Profiles)
Immediate deployment without waiting for Palo Alto Networks to publish a formal App-ID
It’s explicitly recommended in PCNSE prep guides for internal, trusted apps with idle behavior.

❌ Why the other options are incorrect
A. Create custom app with signatures:
Signature development requires packet captures, pattern analysis, and testing—time-consuming and unnecessary if threat inspection isn’t needed.
B. Raise support request:
Submitting a support case may take days or weeks. It’s useful for broader App-ID issues but not ideal for quick internal deployments.
D. Request new App-ID via online form:
This is a long-term solution for public apps. Palo Alto Networks reviews, tests, and releases App-IDs via content updates—not suitable for immediate internal use.

🔗 Reference:
App-ID Overview and Custom Application Management
PCNSE Application Override Best Practices

D. It applies to new sessions and is global.

Explanation:
An engineer is configuring Packet Buffer Protection on ingress zones to protect a Palo Alto Networks firewall from single-session Denial of Service (DoS) attacks, which overwhelm packet buffers by exhausting resources with individual session floods. Packet Buffer Protection, enabled under Device > Setup > Session > Packet Buffer Protection, is a global feature designed to manage data plane resources by limiting the number of packets a single session can buffer. It applies to new sessions because it evaluates and enforces limits as sessions are initiated, preventing resource exhaustion from the outset. The protection is global across the firewall, affecting all interfaces and zones, though its thresholds can be influenced by zone-specific configurations (e.g., via Zone Protection profiles).

Why Other Options Are Incorrect:
A. It applies to existing sessions and is global:
This is incorrect because Packet Buffer Protection does not retroactively apply to existing sessions. It is proactive, targeting new sessions to prevent buffer overflow. The PCNSE Study Guide notes its forward-looking nature.
B. It applies to new sessions and is not global:
This is incorrect because, while it applies to new sessions, Packet Buffer Protection is a global configuration that affects the entire firewall’s data plane, not just specific zones or interfaces unless enhanced by zone profiles. The PAN-OS 11.1 Administrator’s Guide confirms its global scope.
C. It applies to existing sessions and is not global:
This is incorrect for two reasons: it does not apply to existing sessions (as explained above), and it is a global setting, not zone-specific by default. The PCNSE Study Guide clarifies its global application.

Practical Steps:
Navigate to Device > Setup > Session.
Expand Packet Buffer Protection and enable it.
Set global thresholds (e.g., maximum packets per session, burst size) to handle DoS attacks.
Optionally, enhance protection by applying a Zone Protection profile (Network > Zone Protection) to ingress zones, configuring flood protection thresholds.
Commit the configuration.
Monitor buffer utilization via Dashboard > Resources Widget or CLI show running resource-monitor. Verify dropped sessions in Monitor > Threat Logs for DoS-related events.

Additional Considerations:
Adjust thresholds based on normal traffic patterns to avoid false positives.
Combine with Zone Protection profiles for zone-specific tuning if needed.
Ensure PAN-OS version (e.g., 11.1) supports this feature, which it does by default.

References:
Palo Alto Networks PAN-OS 11.1 Administrator’s Guide:
Details Packet Buffer Protection scope.
Palo Alto Networks PCNSE Study Guide:
Explains its application to new sessions.

A. RADIUS
B. TACACS+
E. SAML

Explanation:
A firewall administrator needs to authenticate admins into a Palo Alto Networks Next-Generation Firewall (NGFW) using external authentication services without creating administrator accounts directly on the firewall. This approach leverages centralized identity management, allowing the firewall to query external services for authentication and authorization details, mapping them to local roles via authentication profiles. The supported external services that enable this without local account creation are:

A. RADIUS:
The firewall can use RADIUS (Remote Authentication Dial-In User Service) to authenticate admins by querying a RADIUS server (e.g., FreeRADIUS, Cisco ISE). The authentication profile under Device > Authentication Profile maps RADIUS attributes (e.g., Vendor-Specific Attributes) to roles, eliminating the need for local accounts. The Palo Alto Networks PAN-OS 11.1 Administrator’s Guide confirms RADIUS support for admin authentication. B. TACACS+:
TACACS+ (Terminal Access Controller Access-Control System Plus) provides authentication, authorization, and accounting, allowing the firewall to authenticate admins via a TACACS+ server (e.g., Cisco ACS). An authentication profile maps TACACS+ responses to roles, supporting admin access without local accounts. The PCNSE Study Guide lists TACACS+ as a supported method.
E. SAML:
Security Assertion Markup Language (SAML) enables single sign-on (SSO) authentication using an Identity Provider (IdP) like Okta or Azure AD. The firewall acts as a Service Provider, using a SAML authentication profile (Device > Authentication Profile) to authenticate admins and assign roles based on IdP assertions, avoiding local account creation. The PAN-OS 11.1 Administrator’s Guide details SAML integration.

Why Other Options Are Incorrect:
C. Kerberos:
Kerberos, typically used in Windows AD environments, is not natively supported for admin authentication on the firewall without local account mapping or a User-ID agent. It requires additional configuration (e.g., via LDAP or a custom solution), making it less direct. The PCNSE Study Guide notes its limited use for admin access.
D. LDAP:
While LDAP (Lightweight Directory Access Protocol) can authenticate users via an AD server, it requires creating a local administrator account on the firewall to map the LDAP bind credentials. Without a local account, LDAP cannot authenticate admins directly, as per the PAN-OS 11.1 Administrator’s Guide.

Practical Steps:
Navigate to Device > Authentication Profile.
Create a profile for RADIUS, TACACS+, or SAML.
Configure the server settings (e.g., IP, port, shared secret for RADIUS/TACACS+; IdP metadata for SAML).
Map roles (e.g., superuser) using attributes or group membership.
Apply the profile to admin roles under Device > Administrators (select “None” for local account). Commit and test login via the web UI or CLI.

References:
Palo Alto Networks PAN-OS 11.1 Administrator’s Guide: Details external authentication services.
Palo Alto Networks PCNSE Study Guide: Explains admin authentication options.

A. A secondary DNS server in the DNS proxy is optional, and configuration commit to the firewall will succeed with only one DNS server.

Explanation:
When configuring DNS Proxy for Explicit Proxy (web proxy), the firewall allows you to specify primary and secondary DNS servers. However, the configuration validation only requires a primary DNS server to be defined. The commit operation will succeed with just one DNS server configured.

Why the other options are incorrect:
B. A maximum of two FQDNs can be mapped to an IP address in the static entries for DNS proxy:
This is false. There is no hard-coded limit on the number of FQDNs that can be mapped to a single IP address in the static entries of the DNS proxy configuration.
C. DNS timeout for web proxy can be configured manually, and it should be set to the highest value possible:
This is incorrect and not a best practice. The DNS timeout value should be set appropriately based on network conditions. Setting it to an excessively high value could cause unnecessary delays in DNS resolution and degrade user experience.
D. Adjust the UDP queries for the DNS proxy to allow both DNS servers to be tried within 20 seconds:
This is misleading. The default behavior of the DNS proxy is to query the primary server first, and if no response is received within the configured timeout (default is 2 seconds), it will try the secondary server. The total time for both attempts is not fixed at 20 seconds; it depends on the configured timeout and number of retries.

Reference:
Palo Alto Networks Administrator Guide:
The "DNS Proxy" section confirms that while multiple DNS servers can be configured for redundancy, only one is required for a valid configuration.
PCNSE Exam Blueprint (Domain 2:
Deployment and Configuration): Understanding DNS proxy configuration for explicit proxy deployments is a key objective within the blueprint.

B. Ethernet SGT Protection

Explanation:

Cisco TrustSec and SGT (Security Group Tags)Cisco TrustSec is a security framework that uses Security Group Tags (SGTs) embedded in Layer 2 Ethernet frames to enforce policy-based segmentation
. These SGTs are carried in the Cisco Metadata Exchange (CMDX) or IEEE 802.1AE (MACsec) frames and are used for dynamic access control.
Zone Protection Profile & Ethernet SGT Protection Palo Alto firewalls can inspect and enforce policies based on SGT tags when Ethernet SGT Protection is enabled in the Zone Protection profile.
This setting ensures that:
The firewall identifies and validates SGT-tagged packets.
It can drop, allow, or alert based on the configured action.

Why Not the Other Options?
A. TCP Fast Open (Strip TCP Options)
→ Unrelated to TrustSec (deals with TCP optimization).
C. Stream ID (IP Option Drop)
→ Pertains to IPv4 header options, not Layer 2 SGT.
D. Record Route (IP Option Drop)
→ Also an IPv4 header option, not relevant to TrustSec.

Reference:
Palo Alto Networks Admin Guide (Zone Protection Profile):
Describes Ethernet SGT Protection as the correct setting for handling Cisco TrustSec packets.
Found under:
Network > Network Profiles > Zone Protection > Ethernet SGT Protection

B. Use the Aggressive timer for faster failover timer settings

Explanation:
Palo Alto Networks firewalls use timers to monitor the health of the HA peers and trigger a failover if a peer is detected as failed. These timers are categorized into three predefined sets:

Recommended:
This is the default timer setting. It provides a balance between detecting failures and avoiding false positives caused by temporary network issues. This is the setting you would use for a typical, stable network environment.
Aggressive:
This setting uses the shortest possible timer values. It is designed to provide the fastest possible failover detection. You would use this in environments where downtime is extremely critical and you need to fail over as quickly as possible, even at the risk of a false failover from a minor network fluctuation.
Critical:
This setting uses a failover threshold that is even more stringent than the Aggressive setting. The timer values are so small that they are only applicable in very specific, high-performance environments and can be prone to false positives if not used carefully.
Moderate:
There is no pre-defined "Moderate" timer setting in the Palo Alto Networks HA configuration. The available options are Recommended, Aggressive, and Critical.

Analysis of the Options
A. Use the Critical timer for faster failover timer settings:
While the Critical timer is fast, the Aggressive timer is the most commonly recommended choice for "faster failover" in a typical setup. The Critical timer is a more specialized, extreme setting.
B. Use the Aggressive timer for faster failover timer settings:
This is the correct statement. The Aggressive timer is specifically designed for environments that require faster failover detection than the default "Recommended" setting.
C. Use the Moderate timer for typical failover timer settings:
This is incorrect. There is no "Moderate" timer. The "Recommended" timer is the one used for typical settings.
D. Use the Recommended timer for faster failover timer settings:
This is incorrect. The Recommended timer is the default and is designed for normal operations, not for fast failover. The Aggressive and Critical timers are the options for faster failover