The answer is code signing, as it is the technology that cryptographically ensures only authorized code runs on POS terminals. Code signing works by having a trusted publisher digitally sign executables with a private key, and the terminal verifies that signature against a trusted certificate before allowing execution, effectively blocking any tampered or unapproved software. On the CompTIA SecurityX CAS-004 exam, this question tests your ability to distinguish code signing from related controls like TPM (which handles hardware attestation) and secure boot (which protects boot-time integrity only). A common trap is confusing code signing with application whitelisting—remember that whitelisting is a policy-based allowlist, while code signing is the cryptographic mechanism that enforces trust at the file level. For a memory tip, think “sign before you run” to recall that code signing provides pre-execution verification of publisher identity and file integrity.
CAS-004 Security Engineering Practice Question
This CAS-004 practice question tests your understanding of security engineering. Match the stated requirement to the specific cloud service, access model, or configuration option — many options are valid in isolation but not for this scenario. 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.
A company wants to ensure that only authorized code runs on its point-of-sale (POS) terminals. Which technology should be implemented?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Code signing
Code signing ensures that executables are digitally signed by a trusted publisher, and the system verifies the signature before execution. TPM is for attestation, application whitelisting is a policy, and secure boot focuses on boot-time integrity.
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.
✗
Application whitelisting
Why it's wrong here
Whitelisting is a policy approach but often relies on hashes; code signing provides stronger cryptographic assurance.
✓
Code signing
Why this is correct
Code signing digitally signs executables, and the system validates the signature before allowing execution.
Related concept
Static NAT maps one inside address to one outside address.
✗
Trusted Platform Module (TPM)
Why it's wrong here
TPM can help with attestation but does not directly verify code signatures at runtime.
✗
Secure Boot
Why it's wrong here
Secure Boot only checks the bootloader and OS kernel, not general applications.
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 — This question tests Security Engineering — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Code signing — Code signing ensures that executables are digitally signed by a trusted publisher, and the system verifies the signature before execution. TPM is for attestation, application whitelisting is a policy, and secure boot focuses on boot-time integrity.
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.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Question Discussion
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