This PCNSE practice question tests your understanding of secure access and vpn. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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
admin@PA-5000> show vpn ipsec-sa
Total IPsec SA: 3
Gateway: VPN-GW-1, Tunnel-id: 1, State: active, SPI: 123456, Encapsulation: tunnel
Gateway: VPN-GW-2, Tunnel-id: 2, State: init, SPI: 0, Encapsulation: tunnel
Gateway: VPN-GW-3, Tunnel-id: 3, State: active, SPI: 789012, Encapsulation: transport
Configuration for VPN-GW-2:
set network tunnel ipsec ipsec-crypto VPN-GW-2 ike-gateway VPN-GW-2-IKE
set network tunnel ipsec ipsec-crypto VPN-GW-2 esp-authentication sha1
set network tunnel ipsec ipsec-crypto VPN-GW-2 esp-encryption aes128
set network tunnel ipsec ipsec-crypto VPN-GW-2 lifetime 3600
set network ike gateway VPN-GW-2-IKE version ikev1
set network ike gateway VPN-GW-2-IKE protocol-version ikev1
set network ike gateway VPN-GW-2-IKE peer-address 10.1.1.1
set network ike gateway VPN-GW-2-IKE pre-shared-key mykey
set network ike gateway VPN-GW-2-IKE local-address 10.1.1.2
set network ike gateway VPN-GW-2-IKE local-id 10.1.1.2
set network ike gateway VPN-GW-2-IKE peer-id 10.1.1.1
set network tunnel ipsec ipsec-crypto VPN-GW-2 proxy-id local-ip 192.168.1.0/24
set network tunnel ipsec ipsec-crypto VPN-GW-2 proxy-id remote-ip 192.168.2.0/24
A site-to-site IPsec tunnel between two Palo Alto Networks firewalls is not passing traffic. The administrator runs the 'show vpn ipsec-sa' command and sees the output in the exhibit. The remote peer is configured to use IKEv2 only. Based on the configuration, what is the most likely cause of the tunnel being in 'init' state?
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.
admin@PA-5000> show vpn ipsec-sa
Total IPsec SA: 3
Gateway: VPN-GW-1, Tunnel-id: 1, State: active, SPI: 123456, Encapsulation: tunnel
Gateway: VPN-GW-2, Tunnel-id: 2, State: init, SPI: 0, Encapsulation: tunnel
Gateway: VPN-GW-3, Tunnel-id: 3, State: active, SPI: 789012, Encapsulation: transport
Configuration for VPN-GW-2:
set network tunnel ipsec ipsec-crypto VPN-GW-2 ike-gateway VPN-GW-2-IKE
set network tunnel ipsec ipsec-crypto VPN-GW-2 esp-authentication sha1
set network tunnel ipsec ipsec-crypto VPN-GW-2 esp-encryption aes128
set network tunnel ipsec ipsec-crypto VPN-GW-2 lifetime 3600
set network ike gateway VPN-GW-2-IKE version ikev1
set network ike gateway VPN-GW-2-IKE protocol-version ikev1
set network ike gateway VPN-GW-2-IKE peer-address 10.1.1.1
set network ike gateway VPN-GW-2-IKE pre-shared-key mykey
set network ike gateway VPN-GW-2-IKE local-address 10.1.1.2
set network ike gateway VPN-GW-2-IKE local-id 10.1.1.2
set network ike gateway VPN-GW-2-IKE peer-id 10.1.1.1
set network tunnel ipsec ipsec-crypto VPN-GW-2 proxy-id local-ip 192.168.1.0/24
set network tunnel ipsec ipsec-crypto VPN-GW-2 proxy-id remote-ip 192.168.2.0/24
A
The IKE version is incompatible.
Local uses IKEv1, remote expects IKEv2; Phase 1 negotiation fails, resulting in 'init' state.
B
The pre-shared key is incorrect.
Why wrong: An incorrect PSK would cause IKE authentication failure, but the remote peer's IKE version is explicitly stated as IKEv2 only, making this less likely.
C
The proxy IDs are mismatched with the peer.
Why wrong: Proxy ID mismatch causes Phase 2 failure, not Phase 1; the tunnel would show 'active' for Phase 1.
D
The IPsec crypto profile lifetime is too short.
Why wrong: Lifetime settings affect re-keying, not initial SA establishment.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The IKE version is incompatible.
The 'init' state indicates that IKE Phase 1 has not completed successfully. Since the local firewall is configured for IKEv1 but the remote peer uses IKEv2 only, the IKE version mismatch prevents Phase 1 negotiation. Option A (pre-shared key incorrect) could also cause Phase 1 failure, but the exhibit does not indicate a key mismatch, and the problem statement emphasizes the peer's IKE version. Option B (proxy IDs mismatched) would cause Phase 2 failure, not Phase 1. Option D (lifetime too short) is unlikely to cause a permanent 'init' state; it affects re-keying.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
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 version is incompatible.
Why this is correct
Local uses IKEv1, remote expects IKEv2; Phase 1 negotiation fails, resulting in 'init' state.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
The pre-shared key is incorrect.
Why it's wrong here
An incorrect PSK would cause IKE authentication failure, but the remote peer's IKE version is explicitly stated as IKEv2 only, making this less likely.
✗
The proxy IDs are mismatched with the peer.
Why it's wrong here
Proxy ID mismatch causes Phase 2 failure, not Phase 1; the tunnel would show 'active' for Phase 1.
✗
The IPsec crypto profile lifetime is too short.
Why it's wrong here
Lifetime settings affect re-keying, not initial SA establishment.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Trap categories for this question
Command / output trap
Proxy ID mismatch causes Phase 2 failure, not Phase 1; the tunnel would show 'active' for Phase 1.
Detailed technical explanation
How to think about this question
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
KKey Concepts to Remember
Static NAT maps one inside address to one outside address.
PAT allows many inside hosts to share one public address using ports.
Inside local and inside global describe the private and translated addresses.
NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
→Identify inside and outside interfaces first.
→Check whether the scenario needs static NAT, dynamic NAT or PAT.
→Do not confuse NAT matching ACLs with normal packet-filtering intent.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCNSE NAT questions on configuration and troubleshooting.
Secure Access and VPN — This question tests Secure Access and VPN — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The IKE version is incompatible. — The 'init' state indicates that IKE Phase 1 has not completed successfully. Since the local firewall is configured for IKEv1 but the remote peer uses IKEv2 only, the IKE version mismatch prevents Phase 1 negotiation. Option A (pre-shared key incorrect) could also cause Phase 1 failure, but the exhibit does not indicate a key mismatch, and the problem statement emphasizes the peer's IKE version. Option B (proxy IDs mismatched) would cause Phase 2 failure, not Phase 1. Option D (lifetime too short) is unlikely to cause a permanent 'init' state; it affects re-keying.
What should I do if I get this PCNSE question wrong?
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related PCNSE NAT questions on configuration and troubleshooting.
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?
Static NAT maps one inside address to one outside address.
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