This PCNSE practice question tests your understanding of secure access and vpn. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Exhibit
Refer to the exhibit.
show vpn gateway
Name: Corp-GW
Peer IP: 203.0.113.1
Local IP: 198.51.100.1
IKE version: IKEv2
Pre-shared key: ****
IKE crypto profile: default
DPD: enabled
show vpn tunnel
Name: Corp-Tun
Tunnel interface: tunnel.1
Type: IPSec
IKE gateway: Corp-GW
IPSec crypto profile: default
Proxy IDs: local 10.0.0.0/16, remote 172.16.0.0/16
show routing route
Destination: 172.16.0.0/16
Next hop: tunnel.1
Metric: 10
show interface tunnel.1
Interface: tunnel.1
Zone: VPN-Zone
Virtual router: default
Refer to the exhibit. A site-to-site VPN is configured between two branches. The tunnel is up but traffic is not passing. What is the most likely issue?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Exhibit
Refer to the exhibit.
show vpn gateway
Name: Corp-GW
Peer IP: 203.0.113.1
Local IP: 198.51.100.1
IKE version: IKEv2
Pre-shared key: ****
IKE crypto profile: default
DPD: enabled
show vpn tunnel
Name: Corp-Tun
Tunnel interface: tunnel.1
Type: IPSec
IKE gateway: Corp-GW
IPSec crypto profile: default
Proxy IDs: local 10.0.0.0/16, remote 172.16.0.0/16
show routing route
Destination: 172.16.0.0/16
Next hop: tunnel.1
Metric: 10
show interface tunnel.1
Interface: tunnel.1
Zone: VPN-Zone
Virtual router: default
A
The IKE gateway is not configured with the correct peer IP.
Why wrong: The peer IP is configured.
B
No security policy allows traffic from the VPN zone.
Even though the tunnel is up, traffic can be blocked by security policy if no rule permits it.
C
The proxy IDs do not match the remote peer.
Why wrong: The proxy IDs show correct local and remote subnets.
D
The tunnel interface is not assigned to a zone.
Why wrong: The tunnel interface is in zone VPN-Zone.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
No security policy allows traffic from the VPN zone.
When a site-to-site VPN tunnel is up but traffic is not passing, the most common cause is the absence of a security policy that permits traffic from the VPN zone to the destination zone. Even if IKE and IPsec SAs are established, the firewall drops the decrypted traffic if no rule explicitly allows it. This is a fundamental Palo Alto Networks concept: tunnel establishment and data forwarding are separate control and data plane functions.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
The IKE gateway is not configured with the correct peer IP.
Why it's wrong here
The peer IP is configured.
✓
No security policy allows traffic from the VPN zone.
Why this is correct
Even though the tunnel is up, traffic can be blocked by security policy if no rule permits it.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The proxy IDs do not match the remote peer.
Why it's wrong here
The proxy IDs show correct local and remote subnets.
Common exam trap: answer the scenario, not the keyword
Palo Alto Networks often tests the misconception that a tunnel being up automatically means traffic will pass, but Palo Alto Networks requires an explicit security policy to permit decrypted traffic from the VPN zone.
Trap categories for this question
Command / output trap
The proxy IDs show correct local and remote subnets.
Detailed technical explanation
How to think about this question
In Palo Alto Networks firewalls, IPsec tunnels are established via IKE and IPsec SAs, but the decrypted traffic must still match a security policy rule that allows it from the tunnel's ingress zone (typically the VPN zone) to the egress zone. The firewall checks the source zone of the decrypted packet against the security policy; if no rule matches, the packet is silently dropped. This is distinct from Cisco ASA/FTD where crypto maps implicitly permit traffic once the tunnel is up.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
Quick reference
VPN Protocol Comparison
Protocol
Port
Encryption
Authentication
Use Case
IKEv2 / IPsec
UDP 500 / 4500
AES-256
Certificates / PSK
Site-to-site & remote access
SSL / TLS VPN
TCP 443
TLS 1.3
Certificates / MFA
Clientless remote access
L2TP / IPsec
UDP 1701
AES (IPsec)
PSK / Certificates
Legacy remote access
WireGuard
UDP 51820
ChaCha20
Public keys
Modern high-performance VPN
PPTP
TCP 1723
MPPE (weak)
MS-CHAPv2
Legacy — avoid in production
PPTP is considered insecure. IKEv2/IPsec and SSL VPN are the current recommended options.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Secure Access and VPN — This question tests Secure Access and VPN — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: No security policy allows traffic from the VPN zone. — When a site-to-site VPN tunnel is up but traffic is not passing, the most common cause is the absence of a security policy that permits traffic from the VPN zone to the destination zone. Even if IKE and IPsec SAs are established, the firewall drops the decrypted traffic if no rule explicitly allows it. This is a fundamental Palo Alto Networks concept: tunnel establishment and data forwarding are separate control and data plane functions.
What should I do if I get this PCNSE question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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