Be able to write a playbook that uses serial and max_fail_percentage to roll updates in controlled batches, and predict the exact outcome when a host fails mid-run. The most important thing is knowing that exceeding max_fail_percentage aborts the play for all remaining hosts.
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Coordinate rolling updates — choose a session length
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Domain overview
This domain covers orchestrating safe, staged updates across managed hosts using Ansible playbooks. It is tested through scenario questions on serial batching, failure thresholds, and quorum preservation for stateful services. You must reason about what happens mid-run when a host fails, and choose directives that limit blast radius while keeping services available.
Exam objectives
Using the serial keyword to batch hosts, including values like 1, percentages, or counts
Applying max_fail_percentage to abort a play when a batch exceeds the failure threshold
Ordering tasks with handlers, pre_tasks, and post_tasks to drain and restore nodes
Managing stateful clusters so quorum (for example 3 of 5 nodes) stays online during updates
Confusing max_fail_percentage with serial: the threshold applies per batch, not across the whole host group.
Assuming serial: 1 with max_fail_percentage: 0 continues after a failure; it aborts the entire play immediately.
Forgetting that a failed host is removed from the play, so later batches and handlers may not run as expected.
Click any question to see the full explanation and answer options, or start a focused practice session above.
An operations team is designing a rolling update for a stateful application that requires quorum (minimum 3 out of 5 nodes online). They plan to use Ansible's serial keyword. Which serial value ensures the update proceeds without breaking quorum while still being efficient?
2Which TWO options are best practices for coordinating rolling updates with Ansible? (Choose exactly two.)
3An Ansible Engineer is planning a rolling update for a web application deployed across 10 nodes. The playbook uses the 'delegate_to' directive to manage load balancer health checks. Which of the following best describes the recommended approach to minimize downtime?
4Which TWO of the following are best practices when coordinating rolling updates with Ansible?
5An administrator needs to update a web application that runs as a Kubernetes Deployment with 5 replicas. The application is stateless, but the update must not cause any downtime. Which TWO strategies ensure zero-downtime rolling updates?
6Drag and drop the steps to configure a firewall rule using firewalld to allow HTTPS traffic in the correct order.
7An administrator wants to update a web server fleet with minimal downtime. They need to update each server one at a time. Which Ansible playbook directive should be used?
8During a rolling update using an Ansible playbook with serial: 2, one host in the first batch becomes unreachable. The playbook fails with an unreachable host error. How should the administrator proceed to complete the update on the remaining hosts while excluding the problematic host?
9An administrator notices that during a rolling update, the playbook seems to hang after updating the first host. The playbook uses serial: 5. What is the most likely cause?
10A team uses Ansible to update a database cluster with one primary and two replicas. The goal is zero downtime. Which update order is the safest?
11A company wants to implement a rolling update for a stateful application where hosts cannot be updated in parallel due to data consistency. They also need to ensure that if any host fails, the entire update is rolled back. Which strategy meets these requirements?
12Which THREE statements correctly describe the behavior of the 'serial' keyword in Ansible? (Choose exactly three.)
13A team uses Ansible to update a web application across 10 servers with minimal downtime. Which playbook directive achieves one-at-a-time updates?
14In OpenShift, a DeploymentConfig uses the RollingUpdate strategy. Which parameter controls the maximum number of pods that can be unavailable during an update?
15An Ansible playbook sets 'serial: 20%' for rolling updates, but the inventory contains 5 hosts. How many hosts are updated simultaneously?
16An Ansible rolling update playbook includes 'max_fail_percentage: 20'. If more than 20% of hosts fail during any batch, what happens?
17In OpenShift, a deployment must gradually shift traffic to new pods during a rolling update. Which default strategy achieves this?
18An Ansible rolling update playbook has 'serial: 1' and 'max_fail_percentage: 0'. During the update of a 5-host group, the first host fails. What is the outcome?
19An OpenShift rolling update is failing because new pods crash immediately. Which parameter automatically triggers a rollback if no progress is made?
20A company uses Ansible to perform a rolling update of 10 web servers behind an HAProxy load balancer. The playbook uses the `serial` keyword and includes tasks to disable a host from the load balancer, update the web server package, and re-enable the host. Which TWO best practices should the administrator apply to minimize downtime and ensure a successful rolling update?
21You are performing a rolling update of a 12-node web server fleet managed by Ansible. The playbook uses `serial: 4`. During the second batch, the task `Restart httpd` fails on one host because the service name is misspelled. The playbook aborts with an error. You fix the typo and rerun the playbook. What is the default behavior regarding the hosts that were already updated successfully in the first batch?
22An administrator is designing a rolling update playbook for a 20-node application cluster. The playbook must limit the blast radius of failures and allow the rollout to pause safely if too many hosts fail. Which two Ansible play-level keywords directly control how many hosts are updated at once and whether the play aborts based on failures? (Choose two.)
23You are performing a rolling update on a 5-node application cluster using an Ansible playbook with `serial: 1`. The playbook includes a task that uses the `uri` module to check the application health endpoint after each node is updated. The health check must wait until the application returns HTTP 200 before proceeding to the next node. Which approach ensures that the playbook waits for the health check to succeed before moving to the next host?
24You are designing a rolling update playbook for a 20-node application cluster. The application requires that no more than 25% of the nodes be unavailable at any time. You want Ansible to automatically pause the play if the failure rate within a batch exceeds a threshold, so that you can investigate before continuing. Which play-level keyword should you use?
25A junior administrator needs to perform a rolling update of 8 web servers where exactly 2 servers are updated at a time. Which play-level keyword and value should be used in the Ansible playbook?
26You are writing an Ansible playbook to perform a rolling update of a 20-node RHEL application cluster. The application requires that no more than 20 percent of the fleet be offline at any time. You want the playbook to update hosts in batches that respect this constraint and to abort the entire rollout if the failure rate within any batch exceeds 10 percent. Which combination of play keywords should you use?
27A platform team uses an Ansible playbook with 'serial: "20%"' to roll out a new configuration to 50 hosts. During the third batch, a task fails on several hosts, and the play aborts with a message about max_fail_percentage. Which statement correctly describes how Ansible determined the batch size and the failure threshold in this run?
28You 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?
29You are running an Ansible playbook with `serial: 2` to update a fleet of 6 web servers. The playbook includes a task that restarts the web service. After the first batch of 2 hosts is updated, you notice that both hosts are restarted simultaneously. You want to ensure that within each batch, the hosts are updated one at a time to avoid a temporary loss of capacity. Which Ansible keyword should you add to the play to achieve this?
30You are performing a rolling update of a 15-node RHEL cluster with an Ansible playbook that uses `serial: 5`. During the second batch, a host fails to restart its application service, and the task fails. You want the playbook to stop the entire rollout immediately so that no further batches are updated, allowing you to investigate the failure. Which play keyword should you set to achieve this behavior?
31An administrator is rolling out a configuration change to a fleet of 12 application servers. The change must be applied to one server at a time so that the load balancer always has 11 healthy backends. Which playbook directive guarantees this behavior?
32You are designing a rolling update for a stateful service where each node must be removed from a load balancer, updated, and re-added before the next node is touched. The update must never take more than one node offline at a time, and if the update fails on a node, the play must stop and leave the remaining nodes untouched. Which playbook configuration achieves this?
Deep-dive questions
The most-searched questions in this domain — detailed explanations, worked examples, full answer breakdowns.
Be able to write a playbook that uses serial and max_fail_percentage to roll updates in controlled batches, and predict the exact outcome when a host fails mid-run. The most important thing is knowing that exceeding max_fail_percentage aborts the play for all remaining hosts.
The Courseiva EX294 question bank contains 32 questions in the Coordinate rolling updates domain, covering the 13% of the exam attributed to this domain in the official Red Hat blueprint. Click any question to see the full explanation and answer breakdown.
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