CAS-004 Security Engineering and Cryptography Practice Question
This CAS-004 practice question tests your understanding of security engineering and cryptography. Compare every option against the stated constraints before choosing — the best answer satisfies all requirements, not just the most obvious one. 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 wants to implement passwordless authentication using FIDO2/WebAuthn. Which of the following best describes the primary security advantage of this approach over traditional password-based authentication?
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.
Clue: "primary"
Why it matters: Asks for the main purpose or function, not a secondary benefit. Eliminate answers that describe side-effects or partial functions.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It prevents phishing by using cryptographic keys bound to the origin
FIDO2/WebAuthn uses public key cryptography, so the server does not store a shared secret (password) that can be stolen. This eliminates credential theft via server-side breaches.
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.
✗
It eliminates the need for multi-factor authentication
Why it's wrong here
FIDO2 itself is often considered multi-factor, but it does not eliminate the need for MFA; it provides strong authentication.
✓
It prevents phishing by using cryptographic keys bound to the origin
Why this is correct
FIDO2 credentials are scoped to the relying party origin, making them resistant to phishing attacks.
Clue confirmation
The clue words "best", "primary" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
✗
It allows users to reuse the same password across services
Why it's wrong here
Passwordless does not involve passwords at all.
✗
It requires a hardware token for every login
Why it's wrong here
While hardware tokens are an option, FIDO2 can also use platform authenticators like TPM.
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.
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 CAS-004 NAT questions on configuration and troubleshooting.
Security Engineering and Cryptography — This question tests Security Engineering and Cryptography — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: It prevents phishing by using cryptographic keys bound to the origin — FIDO2/WebAuthn uses public key cryptography, so the server does not store a shared secret (password) that can be stolen. This eliminates credential theft via server-side breaches.
What should I do if I get this CAS-004 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 CAS-004 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "best", "primary". 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?
Static NAT maps one inside address to one outside address.
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