The answer is to use a user-defined network and connect both containers. This resolves the issue because the default bridge network in Podman does not provide automatic DNS resolution between containers by name, and the `--network host` flag on the app container isolates it from container networking entirely, preventing hostname lookups for 'db'. On the CompTIA Linux+ XK0-005 exam, this scenario tests your understanding of Podman container communication and DNS resolution, often appearing as a trap where candidates assume the default bridge works like Docker’s or that host networking still allows container name resolution. A common memory tip is to remember that host networking means the container lives on the host’s IP stack, not on a container network—so it cannot see other containers by name unless they share a user-defined network. Think of it as needing a private subnet with a built-in DNS server: user-defined networks in Podman automatically enable name-based resolution, making them essential for reliable inter-container communication.
XK0-005 Scripting, Containers and Automation Practice Question
This XK0-005 practice question tests your understanding of scripting, containers and automation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
You are managing a containerized microservices environment using Podman. One of the services needs to access a PostgreSQL database running in a separate container. The database container is named 'db' and uses the default bridge network. The application container is launched with the command: podman run -d --name app --network host myapp. The application fails to connect to the database using the hostname 'db'. Which change should you resolve the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Use a user-defined network and connect both containers
The default bridge network in Podman does not provide automatic DNS resolution between containers by name. When the app container uses `--network host`, it shares the host's network stack and is not connected to any container network, so it cannot resolve the container name 'db'. A user-defined network enables built-in DNS resolution, allowing containers to communicate by name. Connecting both containers to the same user-defined network resolves the connectivity issue.
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 a user-defined network and connect both containers
Why this is correct
A user-defined network provides automatic DNS resolution, allowing 'db' to resolve to the database container.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use --link db:db when running app container
Why it's wrong here
--link is deprecated and may not work with remote Podman or newer versions; user-defined networks are preferred.
✗
Set environment variable DB_HOST=localhost
Why it's wrong here
localhost inside the host-network container refers to the host itself, not the database container.
✗
Run app container on the same network as db using --network bridge
Why it's wrong here
The default bridge network does not provide DNS resolution; containers can only communicate via IP addresses.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that the default bridge network supports automatic DNS resolution by container name, when in reality only user-defined networks provide that feature in both Podman and Docker.
Detailed technical explanation
How to think about this question
Podman's default bridge network uses CNI (Container Network Interface) plugins and does not include an embedded DNS server. User-defined networks leverage a DNS resolver (e.g., dnsname plugin) that automatically registers container names as A records, enabling name-based communication. In contrast, `--network host` binds the container directly to the host's network interfaces, bypassing any container network isolation and DNS resolution for container names.
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 practitioner preparing for the XK0-005 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
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: Use a user-defined network and connect both containers — The default bridge network in Podman does not provide automatic DNS resolution between containers by name. When the app container uses `--network host`, it shares the host's network stack and is not connected to any container network, so it cannot resolve the container name 'db'. A user-defined network enables built-in DNS resolution, allowing containers to communicate by name. Connecting both containers to the same user-defined network resolves the connectivity issue.
What should I do if I get this XK0-005 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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