EX294 Coordinate rolling updates Practice Question
You are performing a rolling update of a 6-node RHEL web server fleet using an Ansible playbook. The playbook currently uses `serial: 1` and takes a long time because each host is updated sequentially. You want to update two hosts at a time to reduce the total rollout duration while still keeping at least four hosts serving traffic. Which change should you make?
⚠ Common exam trap
It's easy for candidates to confuse concurrency controls like forks or throttle with the serial keyword, which is the actual mechanism that defines rolling update batch size.
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
✓
Change `serial: 1` to `serial: 2`.
To update two hosts at a time in a six-node fleet while keeping four hosts online, the serial batch size must be two. Changing serial from 1 to 2 directly controls how many hosts Ansible targets per play iteration, halving the number of batches and shortening the rollout. Other keywords such as throttle and forks affect concurrency of task execution but do not define rolling update batch boundaries.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Change `serial: 1` to `serial: 2`.
Why this is correct
Changing serial from 1 to 2 updates two hosts per batch, leaving four hosts online at all times, which satisfies the requirement to keep at least four hosts serving traffic. It halves the number of batches compared to serial of 1, reducing the total rollout time while respecting the availability constraint.
- ✗
Add `forks: 2` to the play.
Why it's wrong here
forks controls the number of parallel worker processes Ansible uses for task execution across all hosts, not the size of a rolling update batch. Setting forks to 2 does not change how serial batches are formed and can even reduce parallelism. It does not achieve the goal of updating two hosts per batch.
- ✗
Change `serial: 1` to `serial: 4`.
Why it's wrong here
A serial of 4 would update four hosts simultaneously, leaving only two hosts online, which violates the requirement to keep at least four hosts serving traffic. Although it would reduce rollout time, it breaks the availability constraint and is therefore incorrect for this scenario.
- ✗
Add `throttle: 2` to the play.
Why it's wrong here
The throttle keyword limits how many hosts execute a task concurrently but does not define rolling update batches. It does not change the serial batch size, so the play still processes hosts according to serial, and the rollout duration and availability characteristics remain unchanged. It is not the correct way to widen the batch.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Red Hat exam blueprint
This EX294 practice question is part of Courseiva's free Red Hat 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 EX294 exam.