Question 13 of 968
hardMultiple SelectObjective-mapped
CAS-004 Secure container runtime Practice Question
A security assessor is reviewing a containerized application. Which three of the following practices help secure the container runtime environment? (Select the three best options.)
⚠ Common exam trap
CompTIA often tests the distinction between image security (e.g., using latest images) and runtime security (e.g., read-only filesystem, capability dropping, non-root user), and the trap here is that candidates may incorrectly select 'use the latest base image' because they conflate image freshness with runtime hardening.
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
✓
Run the container with a read-only root filesystem
Running a container with a read-only root filesystem (option A) prevents any writes to the container's filesystem layer, which blocks malware from dropping files, modifying binaries, or persisting changes. This is enforced by the container runtime (e.g., Docker, containerd) by mounting the root filesystem as read-only, typically using the `--read-only` flag. Even if an attacker gains code execution inside the container, they cannot alter system files or install tools, significantly reducing the blast radius of a compromise.
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 the latest base image from Docker Hub
Why it's wrong here
This is important for image security, not runtime configuration.
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-005 exam frequently reuses these exact scenarios with slightly different constraints.
✓Run the container with a read-only root filesystemCorrect answer▾
✗Use the latest base image from Docker HubWrong answer — click to see why▾
Why this is wrong here
This is important for image security, not runtime configuration.
Analysis generated from the official CAS-005blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Quick reference
AAA Protocol Comparison
| Protocol | Port(s) | Encryption | Transport | Primary Use |
|---|---|---|---|---|
| RADIUS | 1812 / 1813 | Password only | UDP | Network access control |
| TACACS+ | 49 | Full packet | TCP | Device administration |
| Diameter | 3868 | Full session | TCP / SCTP | Carrier / mobile networks |
| 802.1X | — | EAP-based | Layer 2 | Port-based access control |
TACACS+ encrypts the entire packet; RADIUS only encrypts the password field — a key exam distinction.
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Last reviewed: Jun 30, 2026
This CAS-005 practice question is part of Courseiva's free CompTIA 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 CAS-005 exam.
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