B. Obtain or generate the server certificate and private key from the datacenter server

Explanation:
To securely inspect inbound SSL traffic destined for applications hosted in an on-premises datacenter, the administrator must configure SSL Inbound Inspection. This requires the firewall to decrypt traffic after the SSL handshake, which means it must possess the actual server certificate and private key used by the datacenter application server.
This enables the firewall to impersonate the server during decryption, inspect the traffic, and then forward it securely. Without the private key, inbound decryption is not possible.
This requirement is documented in Palo Alto Networks’ SSL Inbound Inspection guide and reinforced in PCNSE prep materials2.

❌ Why the other options are incorrect
A. HA3 interfaces for decrypted session sync:
HA3 is used for packet forwarding between HA peers—not for syncing decrypted sessions. Session sync occurs over HA2/HA4 depending on the HA mode, and decrypted session sync is not a prerequisite for configuring decryption policy.
C. Self-signed certificate in the firewall:
This is used for forward proxy decryption (outbound traffic), not inbound. It allows the firewall to re-sign certificates for outbound SSL traffic, but has no role in inspecting inbound traffic to internal servers.
D. Forward trust/untrust certificates from datacenter server:
These are used in forward proxy scenarios to re-encrypt outbound traffic. They are generated and managed on the firewall—not obtained from the datacenter server—and are irrelevant to inbound inspection.

D. Use the Recommended profile for typical failover timer settings

Explanation:
Palo Alto Networks firewalls offer HA timer profiles to simplify failover configuration in high availability (HA) deployments. These profiles predefine timer values that control how quickly the firewall detects peer failure and initiates failover.

The available profiles are:
1.Recommended:
Designed for typical failover behavior
Balances responsiveness with stability
Avoids unnecessary failovers due to transient issues
Best suited for most production environments
2.Aggressive:
Enables faster failover
Useful in environments where rapid recovery is critical
May increase risk of false failovers due to brief link flaps
3.Advanced:
Allows manual customization of all HA timers
Ideal for complex or fine-tuned deployments
There is no “Critical” or “Moderate” profile in PAN-OS HA timer settings, making options A and B invalid.

❌ Why the Other Options Are Incorrect:
A. Critical profile
→ No such profile exists in PAN-OS
B. Moderate profile
→ Also not a valid profile name
C. Aggressive profile for slower failover
→ Incorrect; Aggressive is for faster failover

📚 Reference:
HA Timer Profiles – Palo Alto Networks Documentation
Let me know if you want to simulate failover behavior or explore how HA timers interact with path monitoring and preemption.

C. Check whether the VPN peer on one end is set up correctly using policy-based VPN

Explanation:
The error message specifically indicates a mismatch during IKE Phase-2 negotiation related to the Proxy IDs. Proxy IDs are used to identify the traffic selectors for the IPsec tunnel.

Root Cause:
This error commonly occurs when there is a fundamental mismatch in VPN configuration types between the two peers:
One peer is configured for Policy-Based VPN (which uses explicit Proxy IDs defined in the security policy).
The other peer is configured for Route-Based VPN (which uses implicit Proxy IDs based on the tunnel interface's subnet and often defaults to 0.0.0.0/0 if not explicitly defined).
The firewall is reporting that it received a Proxy ID proposal (local id 192.168.33.33/24, remote id 172.16.33.33/24) that does not match its own configured traffic selectors.

Why the Other Options Are Incorrect:
A. In the IKE Gateway configuration, verify that the IP address for each VPN peer is accurate:
This error is from Phase-2, which occurs after Phase-1 is successful. If the peer IPs were wrong, the negotiation would fail in Phase-1 with an authentication or connectivity error, not a Proxy ID error in Phase-2.
B. Verify that the IP addresses can be pinged and that routing issues are not causing the connection failure:
Again, the error is from Phase-2, meaning Phase-1 completed successfully. This proves basic IP connectivity and IKE authentication worked. The issue is not reachability but a policy mismatch.
D. In the IPSec Crypto profile configuration, verify that PFS is either enabled on both VPN peers or disabled on both VPN peers:
A PFS (Perfect Forward Secrecy) mismatch would cause a Phase-2 failure, but the error message would typically mention a DH group mismatch or proposal mismatch, not a Proxy ID mismatch. The error text explicitly points to the Proxy ID as the problem.

Reference:
Palo Alto Networks Knowledge Base Article #000021509 - "Troubleshooting IKE Phase 2 Failures": This article explicitly lists "Proxy ID mismatch" as a common cause of Phase-2 failures. It states that this often happens when connecting a policy-based VPN (which requires explicit Proxy IDs) to a route-based VPN (which may use automatic or default Proxy IDs like 0.0.0.0/0). The solution is to ensure both ends are configured for the same VPN paradigm or to manually configure matching Proxy IDs on the route-based peer.

D. Values in Chicago

Explanation:
In Panorama, when multiple templates are combined into a template stack, the firewall inherits configuration values based on template priority. The template at the top of the stack has the highest precedence, and its values override those in lower-priority templates if the same object (e.g., SSL/TLS Service profile named "Management") is defined in multiple templates.

According to the retrieved reference:
"The firewall will inherit the settings from the highest priority template that has the setting configured, and ignore the settings from the lower priority templates that have the same setting configured."
So, if all four templates in the stack (Global Settings, Datacenter, efwOlab.chi, and Chicago) define an SSL/TLS Service profile named Management, the firewall will use the version from the Chicago template—assuming it is highest in the stack.

🔗 Authoritative Reference:
Palo Alto Networks TechDocs: Templates and Template Stacks
Cramkey PCNSE Lab Discussion: SSL/TLS Profile Inheritance

C. Certificate Profile
D. CA certificate

Explanation:
To configure certificate-based authentication for administrator access to the web UI on a trusted interface, two key components are required:

✅ C. Certificate Profile
This profile defines how the firewall validates client certificates.
It specifies the CA certificate used to verify the client certificate and maps certificate fields (e.g., Subject) to usernames.
Configured under Device > Certificate Management > Certificate Profile.

✅ D. CA Certificate
This is the root or intermediate certificate that signed the administrator’s client certificate.
It must be imported or generated on the firewall and added to the Certificate Profile.
Used to validate the authenticity of the client certificate during login.

❌ Why Other Options Are Incorrect:
A. Server Certificate Required for SSL/TLS encryption, not for client certificate authentication. It secures the web UI but doesn’t validate admin identity.
B. SSL/TLS Service Profile Used to bind the server certificate to the web interface. It’s necessary for HTTPS access but not directly involved in certificate-based authentication logic.

🔗 Valid References:
Palo Alto Networks TechDocs: Configure Certificate-Based Administrator Authentication to the Web Interface
Pass4Success PCNSE Discussion: Certificate-Based Authentication Requirements

A. > show counter global filter packet-filter yes delta yes

Explanation:
When a packet capture filter is applied, the firewall creates internal counters to track how packets matching that filter are processed. The command show counter global filter packet-filter yes delta yes is the precise tool to investigate these drops. Here's why:

filter packet-filter yes:
This limits the output to only show counters that are influenced by the active packet capture filters. This directly correlates to the drops you are seeing for traffic matching your filter (e.g., source IP 10.1.1.1).
delta yes: This shows the change in counter values since the last time the command was executed. This is crucial for real-time troubleshooting, as it allows you to see which specific drop reasons are incrementing now for your filtered traffic.
The output will list drop counters (e.g., drop_packet_filter_match, drop_deny, etc.) and their delta values, pinpointing the exact reason the packets from 10.1.1.1 are being dropped.


Why the Other Options Are Incorrect:
B. > show counter global filter severity drop
Incorrect. This is not a valid command syntax. The show counter global command does not have a severity filter parameter. Drop counters are not classified by "severity" in this context.
C. > debug dataplane packet-diag set capture stage drop
Incorrect. This command is used to configure a new packet capture that will capture packets at the point they are dropped. It is a powerful tool but does not show you aggregated counter data. It gives you the raw packets that were dropped, not a summary of why they were dropped or how many times it happened.
D. > show counter global filter delta yes I match 10.1.1.1
Incorrect. This command is syntactically invalid. The show counter global command filters based on counter names (e.g., drop), not based on the content of the packets (like IP addresses). You cannot use match with this command.

Reference:
As per the PAN-OS CLI Reference Guide, the show counter global command with the filter packet-filter yes option is explicitly designed to "Display counters that are affected by the packet filter." This makes it the canonical method for investigating drops related to an ongoing packet capture. The delta option is essential for monitoring changes over time.

C. The application has been identified as web-browsing.
D. The session did not go through SSL decryption processing.

Explanation:
Analyzing the session details from the show session id 380280 output:

C. The application has been identified as web-browsing.
The output explicitly states: application : web-browsing. This confirms that App-ID successfully classified the traffic.

D. The session did not go through SSL decryption processing.
The output shows: session proxied : True. This indicates the session was processed by the firewall's proxy (e.g., for security profiles like Threat Prevention, URL Filtering).
However, there is no mention of decryption (e.g., no decrypted flag or SSL-specific fields). Crucially, the source and destination IPs in the s2c flow are different from the c2s flow, and NAT is applied (address/port translation : source), but this is unrelated to decryption.
If SSL decryption had occurred, the output would typically show details like the decryption policy, certificate information, or a decrypted marker. Its absence indicates the traffic was not decrypted.

Why the Other Options Are Incorrect:
A. The session went through SSL decryption processing.:
There is no evidence of decryption in the output. The proxied flag refers to L7 processing (e.g., security profiles), not specifically to decryption.
B. The session has ended with the end-reason unknown.:
The output shows state : ACTIVE and time to live : 2 sec, meaning the session is still active and has not ended. The end-reason field is only relevant after a session closes.

Reference:
PAN-OS session diagnostics: The show session id command provides detailed session attributes. The absence of decryption-related fields (e.g., decryption policy, ssl-decrypt) indicates no decryption occurred (PAN-OS CLI Reference Guide). The application field confirms App-ID results.