The answer is to enable content trust and require signatures on all images. This is the most effective method because content trust, implemented through tools like Docker Content Trust or Notary, cryptographically signs container images, allowing the CI/CD pipeline to verify both the integrity and the publisher’s identity before deployment. On the CompTIA SecurityX CAS-004 exam, this concept tests your understanding of supply chain security and software assurance within DevSecOps pipelines—a common trap is confusing image scanning for vulnerabilities with image signing, but scanning only finds known flaws, while signing prevents unauthorized or tampered images from being deployed at all. Remember the mnemonic: “Sign before you ship, scan after you build” to keep the order straight on exam day.
CAS-004 Ensure only signed images deployed Practice Question
This CAS-004 practice question tests your understanding of scripting, containers and automation. 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 implements a CI/CD pipeline that automatically builds and deploys containerized microservices. Which of the following is the most effective method to ensure that only signed, trusted container images are deployed to production?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Enable content trust and require signatures on all images
Option B is correct because enabling content trust (e.g., Docker Content Trust or Notary) cryptographically signs container images, ensuring that only images signed by a trusted publisher can be deployed. This directly enforces integrity and authenticity in the CI/CD pipeline, preventing unauthorized or tampered images from reaching production.
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.
✗
Implement a private container registry with access controls
Why it's wrong here
Access controls prevent unauthorized pushes but do not verify the integrity or authenticity of images.
✗
Run vulnerability scanning on all images before deployment
Why it's wrong here
Scanning identifies vulnerabilities but does not verify the publisher's identity or prevent tampering.
✗
Use an admission controller that checks image labels
Why it's wrong here
Labels are metadata and can be easily spoofed; they do not provide cryptographic proof of origin.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The CAS-004 exam frequently reuses these exact scenarios with slightly different constraints.
✓Enable content trust and require signatures on all imagesCorrect answer▾✗Implement a private container registry with access controlsWrong answer — click to see why▾
Why this is wrong here
Access controls prevent unauthorized pushes but do not verify the integrity or authenticity of images.
✗Run vulnerability scanning on all images before deploymentWrong answer — click to see why▾
Why this is wrong here
Scanning identifies vulnerabilities but does not verify the publisher's identity or prevent tampering.
✗Use an admission controller that checks image labelsWrong answer — click to see why▾
Why this is wrong here
Labels are metadata and can be easily spoofed; they do not provide cryptographic proof of origin.
Analysis generated from the official CAS-004blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates confuse access control (registry permissions) or vulnerability scanning with cryptographic trust, failing to recognize that only content trust provides non-repudiation and tamper-evidence for container images.
Detailed technical explanation
How to think about this question
Content trust leverages a delegation-based signing model using a root key, target keys, and snapshot keys, typically implemented via Notary or Docker Content Trust. When enabled, the client verifies the signature against a trusted root certificate before pulling or deploying, and the CI/CD pipeline must sign images with a private key during the build stage. In a real-world scenario, a compromised build server could inject malware into an unsigned image, but content trust would reject it at deployment time, even if the image passed vulnerability scans.
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 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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Scripting, Containers and Automation — This question tests Scripting, Containers and Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Enable content trust and require signatures on all images — Option B is correct because enabling content trust (e.g., Docker Content Trust or Notary) cryptographically signs container images, ensuring that only images signed by a trusted publisher can be deployed. This directly enforces integrity and authenticity in the CI/CD pipeline, preventing unauthorized or tampered images from reaching production.
What should I do if I get this CAS-004 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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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