hardMultiple ChoiceObjective-mapped
PCNSA Practice Question: A company has deployed PA-220 firewalls at 50…
A company has deployed PA-220 firewalls at 50 branch offices, each connected to the corporate headquarters via IPSec VPN tunnels. Recently, users have reported slow file transfers across the VPN, especially for large files. The network team has checked link utilization and found that the VPN tunnel bandwidth is under 20% utilized, and CPU on the firewalls is around 40%. The security policies are basic, with no threat prevention profiles applied to the VPN traffic. The team suspects the issue is related to VPN performance. After reviewing the configuration, they notice that the VPN tunnels are configured with default settings. Which of the following actions would most likely improve VPN throughput without requiring hardware upgrades or changing the security level?
⚠ Common exam trap
Candidates often assume stronger encryption (like AES-256-GCM) improves performance or that increasing MTU always helps, when in fact the default settings disable hardware acceleration, which is the primary lever for boosting VPN throughput without hardware changes.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable hardware acceleration for the VPN tunnel on the branch firewalls.
The PA-220 firewall includes hardware acceleration for IPsec VPN processing, but this feature is not enabled by default. Enabling hardware acceleration offloads cryptographic operations to dedicated hardware, significantly improving throughput for large file transfers without requiring hardware upgrades or reducing security. Since the VPN tunnel bandwidth is underutilized and CPU is moderate, the bottleneck is likely software-based encryption, which hardware acceleration directly addresses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Enable hardware acceleration for the VPN tunnel on the branch firewalls.
Why this is correct
Hardware acceleration offloads encryption to dedicated chips, boosting throughput significantly.
- ✗
Upgrade the branch office firewalls to PA-800 series appliances.
Why it's wrong here
Upgrading hardware is expensive and not immediately needed; the PA-220 can be configured to perform better.
- ✗
Change the VPN IPSec cipher suite to use AES-256-GCM for stronger encryption.
Why it's wrong here
While AES-256-GCM is strong, it may not improve throughput; hardware acceleration has a greater impact.
- ✗
Increase the MTU on the VPN tunnel interface to 1500 bytes to reduce fragmentation.
Why it's wrong here
Increasing MTU may cause fragmentation in the network path, potentially worsening performance; MTU should be correctly set based on the path.
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.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PCNSA practice question is part of Courseiva's free Palo Alto Networks certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the PCNSA exam.