The answer is enabling Perfect Forward Secrecy (PFS) and using AES encryption with a minimum key size of 128 bits. PFS ensures that if a long-term private key is compromised, past session keys remain secure because each session generates a unique, ephemeral key through Diffie-Hellman exchanges, preventing an attacker from decrypting historical traffic. AES-128 provides strong, symmetric encryption resistant to known cryptographic attacks and is NIST-approved for protecting sensitive data over untrusted networks like the internet. On the Systems Security Certified Practitioner (SSCP) exam, this question tests your grasp of cryptographic controls within the Cryptography domain, often appearing as a multi-select scenario where common traps include choosing outdated algorithms like DES or 3DES, or omitting PFS in favor of simpler key management. Remember the memory tip: “PFS protects past sessions, AES-128 protects present data”—if you see any key size below 128 bits or a lack of ephemeral key exchange, eliminate those options immediately.
SSCP Network and Communications Security Practice Question
This SSCP practice question tests your understanding of network and communications security. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
An organization is implementing a new remote access VPN for employees using IPsec. Which TWO of the following are best practices for securing the IPsec VPN?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "best"
Why it matters: Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use AES encryption with a minimum key size of 128 bits
AES encryption with a minimum key size of 128 bits is a best practice for IPsec VPNs because it provides strong, symmetric encryption that is resistant to known cryptographic attacks. AES-128 is approved by NIST and widely considered secure for protecting sensitive data over untrusted networks like the internet.
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.
✓
Use AES encryption with a minimum key size of 128 bits
Why this is correct
AES-128 is a strong, recommended encryption algorithm for IPsec.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use pre-shared keys for authentication
Why it's wrong here
Pre-shared keys are weaker and harder to manage than certificate-based authentication.
✗
Disable anti-replay protection to improve performance
Why it's wrong here
Anti-replay protection is a critical security function and should never be disabled.
✓
Enable Perfect Forward Secrecy (PFS)
Why this is correct
PFS ensures session keys are not derived from long-term keys, so compromise of one session key does not compromise future sessions.
Clue confirmation
The clue word "best" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Allow all IP protocols through the VPN tunnel
Why it's wrong here
Allowing all protocols expands the attack surface; only necessary protocols should be permitted.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse pre-shared keys as a secure authentication method for IPsec, but the SSCP exam emphasizes that PSKs are weak compared to digital certificates or EAP methods, especially in enterprise environments.
Detailed technical explanation
How to think about this question
Perfect Forward Secrecy (PFS) ensures that if a long-term private key is compromised, past session keys cannot be derived because each session uses ephemeral Diffie-Hellman (DH) keys that are not stored. In IPsec, PFS is enabled by setting the 'pfs' parameter in the IKE phase 2 policy, which forces a new DH exchange for each Quick Mode negotiation, typically using DH groups 14 (2048-bit) or higher for strong security.
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 developer is choosing between AES-256 (symmetric) and RSA-2048 (asymmetric) for encrypting a large file that will be sent to a partner. Symmetric encryption is fast but requires key exchange; asymmetric is slower but solves the key distribution problem. A hybrid approach — encrypt the file with AES, encrypt the AES key with RSA — is standard. Questions like this test whether you understand when each approach applies.
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.
Network and Communications Security — This question tests Network and Communications Security — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Use AES encryption with a minimum key size of 128 bits — AES encryption with a minimum key size of 128 bits is a best practice for IPsec VPNs because it provides strong, symmetric encryption that is resistant to known cryptographic attacks. AES-128 is approved by NIST and widely considered secure for protecting sensitive data over untrusted networks like the internet.
What should I do if I get this SSCP 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: "best". Signals that multiple options may be partially correct. Choose the option that most directly solves the exact problem described, not the one that sounds most complete.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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