EX294 Practice Test 23 — 15 Questions

Question 1

You 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?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

The playbook starts over from the first batch and processes all hosts again, applying tasks to hosts that were already updated.. Ansible does not persist playbook progress between runs. When you rerun a playbook, it targets the entire inventory by default, so hosts from the first batch are processed again. To avoid re-updating already-successful hosts, you would need to use `--limit` with a list of remaining hosts or implement a custom serial strategy that records completed batches externally.

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The playbook re-runs all tasks on every host, including the first batch, because Ansible is idempotent and will simply reapply the configuration.

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The playbook fails immediately because the inventory still marks the failed host as unreachable, blocking any further execution.

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The playbook resumes from the failed batch, skipping the first batch entirely, because Ansible tracks successful hosts in a fact cache.

Question 2

An automation team wants to build an execution environment that includes a specific collection from a private Automation Hub. Which file must be present in the build context to specify the collection and its source?

Accepted Answer

requirements.yml. To include a collection in an execution environment, `ansible-builder` reads `requirements.yml` from the build context. This file lists collections (and roles) to install, and can specify the source server, making it the correct place to declare a collection from a private Automation Hub.

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execution-environment.yml

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galaxy.yml

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bindep.txt

Question 3

A playbook reads a YAML configuration file with the `include_vars` module and registers the result. The variable `app_config` now holds a dictionary with keys `database`, `cache`, and `logging`. You need to produce a list containing only the top-level key names for a later loop. Which Jinja2 filter expression should you use in the task that builds this list?

Accepted Answer

{{ app_config | dict2items | map(attribute='key') | list }}. To turn dictionary keys into a list, the canonical approach is to convert the dictionary to a list of `{key, value}` dictionaries with `dict2items`, then extract the `key` attribute using `map`. The resulting list can be looped over directly. Filters like `items2dict`, `flatten`, and `subelements` operate on different data shapes and do not produce top-level key names from a plain dictionary.

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{{ app_config | subelements('key') | map(attribute='key') | list }}

Question 4

You 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?

Accepted Answer

Use the uri module with retries and until to repeatedly check the endpoint until it returns HTTP 200.. To ensure the playbook waits for the application to become healthy after each node update, you should use the uri module with retries and until. This combination repeatedly polls the health endpoint until it returns HTTP 200 or the retries are exhausted. This approach is reliable and ensures that the application is ready before proceeding to the next node in the rolling update.

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Use the wait_for module with the host and port parameters to wait for the application to start listening.

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Use the uri module with the status_code parameter set to 200 and register the result, then use a wait_for condition on the result.

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Use the pause module to wait for a fixed amount of time after updating each node.

Question 5

You 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?

Accepted Answer

`serial: 20%` and `max_fail_percentage: 10`. The requirement is to cap concurrent offline hosts at 20 percent of the fleet while aborting when batch failures exceed 10 percent. With 20 nodes, 20 percent equals 4 hosts, so `serial: 20%` expresses the constraint as a percentage that scales with inventory size. `max_fail_percentage: 10` then aborts the play when more than 10 percent of the hosts in the current batch fail. Together they encode both the availability and failure-tolerance policies directly in the play.

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`serial: 4` and `max_fail_percentage: 25`

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`serial: 4` and `max_fail_percentage: 10`

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`serial: 20` and `max_fail_percentage: 10`

Question 6

A 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?

Accepted Answer

The batch size was 10 hosts, and the failure threshold was evaluated against the 10 hosts in the current batch.. When serial is a percentage, Ansible multiplies that percentage by the total number of hosts in the play to determine each batch size. For 50 hosts at 20%, each batch contains 10 hosts. max_fail_percentage is then evaluated against the current batch, so the abort decision is based on failures among those 10 hosts, not the full inventory.

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The batch size was 5 hosts, and the failure threshold was evaluated against the 5 hosts in the current batch.

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The batch size was 20 hosts, and the failure threshold was evaluated against 50 hosts.

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The batch size was 10 hosts, and the failure threshold was evaluated against all 50 hosts regardless of batch.

Question 7

A task registers the output of a command that returns a string containing a JSON document in `result.stdout`. You must extract the numeric value at `metrics.cpu.load` and use it as an integer in a subsequent comparison. Which expression correctly parses the string and retrieves the integer value?

Accepted Answer

{{ result.stdout | from_json | json_query('metrics.cpu.load') | int }}. The correct order is to parse the raw JSON string first with `from_json`, then traverse the nested structure with `json_query`, and finally cast the extracted value with `int`. Reversing or substituting `to_json` breaks the pipeline because it serializes rather than parses. Using `map` is inappropriate for a single dictionary input, and querying before parsing cannot succeed on a raw string.

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{{ result.stdout | json_query('metrics.cpu.load') | from_json | int }}

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{{ result.stdout | to_json | json_query('metrics.cpu.load') | int }}

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{{ result.stdout | from_json | map(attribute='metrics.cpu.load') | int }}

Question 8

You 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?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

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.

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Add `forks: 2` to the play.

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Change `serial: 1` to `serial: 4`.

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Add `throttle: 2` to the play.

Question 9

A playbook registers the output of a command that returns a JSON string inside stdout. The string contains a top-level key 'services' with a nested list of dictionaries. You need to convert that string into native data so you can select only entries where the 'state' key equals 'running'. Which expression accomplishes this?

Accepted Answer

{{ (command_result.stdout | from_json).services | selectattr('state', 'equalto', 'running') | list }}. Parsing the JSON string with from_json is required before any attribute-based filtering can occur. Once parsed, the nested list must be dereferenced through the 'services' key. Only then can selectattr compare each dictionary's 'state' value to 'running' and return the matching subset as a list.

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{{ command_result.stdout | from_json | selectattr('state', 'equalto', 'running') | list }}

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{{ command_result.stdout | from_json | map(attribute='services') | selectattr('state', 'equalto', 'running') | list }}

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{{ command_result.stdout | to_json | selectattr('state', 'equalto', 'running') | list }}

Question 10

An automation engineer has written a custom Ansible role called `db_deploy` and wants to package it inside a new collection named `acme.database`. Which command initializes the collection skeleton with the correct directory layout for roles, modules, and plugins?

Accepted Answer

ansible-galaxy collection init acme.database. Scaffolding a new collection requires the dedicated `ansible-galaxy collection init` subcommand, which generates the namespace/name directory tree plus a `galaxy.yml` manifest. Role initialization, building, and installing all operate on artifacts that already exist and therefore cannot produce the initial skeleton needed before a custom role is placed under `roles/`.

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ansible-galaxy role init acme.database

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ansible-galaxy collection build acme.database

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ansible-galaxy collection install acme.database

Question 11

An automation engineer must ensure that a task in a playbook runs only once across all hosts in the play, even though the play targets 50 web servers. The task creates a shared DNS record on an external service. Which approach should be used?

Accepted Answer

Add `run_once: true` to the task.. The `run_once` directive ensures that a task is executed only on the first host in the play, and the results are applied to all hosts. This is ideal for actions that should not be repeated per host, such as creating a shared resource. Other options either still execute per host or only control concurrency.

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Set `serial: 1` on the play.

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Use `delegate_to: localhost` on the task.

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Add `throttle: 1` to the task.

Question 12

You 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?

Accepted Answer

`throttle: 1` on the restart task. The `throttle` keyword limits the number of concurrent executions of a task across all hosts. By setting `throttle: 1` on the restart task, you ensure that only one host restarts the web service at a time, even within a batch of 2. This maintains the rolling update's goal of minimizing downtime while keeping the batch size efficient.

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`order: inventory` at the play level

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`serial: 1` at the play level

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`strategy: linear` at the play level

Question 13

You maintain a variable inventory_hostnames that is a list of FQDN strings such as 'web01.example.com'. A template must produce a new list containing only the hostname portion before the first dot for each entry, preserving order. Which Jinja2 expression using Ansible filters achieves this?

Accepted Answer

{{ inventory_hostnames | map('regex_replace', '^(.*?)\..*$', '\1') | list }}. Transforming each element of a list while preserving order is best done with map combined with a transformation filter. regex_replace with a capture group extracts the portion before the first dot for every FQDN, and list materializes the generator so the template emits an actual list. Selecting or joining would either leave the strings unchanged or collapse the collection, so mapping is the appropriate technique.

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{{ inventory_hostnames | join('.') | regex_replace('\..*$', '') }}

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Question 14

A company uses dynamic inventory from a cloud provider. The playbook needs to run tasks only on instances with a specific tag. The ansible_ec2_tags variable is not available. What is the most efficient method to filter hosts?

Accepted Answer

Use the amazon.aws.aws_ec2 inventory plugin with compose and keyed_groups.. The `amazon.aws.aws_ec2` inventory plugin can dynamically filter EC2 instances by tag using `keyed_groups` and `compose` at inventory build time, avoiding runtime overhead. This is the most efficient method as it pre-filters hosts before the playbook runs, unlike runtime fact gathering or lookups.

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Use the hostvars lookup to check tags.

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Use the ec2_instance_facts module inside the playbook to gather facts and filter.

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Use a static inventory file with hosts pre-filtered.

Question 15

A playbook must merge a base dictionary of defaults with an override dictionary, where the override may contain nested dictionaries that should be merged recursively rather than replaced. Which filter expression performs a recursive merge?

Accepted Answer

{{ base | combine(override, recursive=True) }}. The combine filter merges dictionaries, and its recursive parameter controls whether nested dictionaries are merged deeply or replaced. For nested overrides that must preserve base subkeys, recursive=True is required. Parameters like list_merge affect list handling only and do not enable recursive dictionary merging.

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