The answer is that the playbook is missing the connection parameter set to 'network_cli'. The ios_config module requires this specific connection transport to properly interface with a network device’s CLI; without it, Ansible defaults to the 'smart' connection plugin, which may execute tasks without errors but fails to push configuration changes like ACLs to the device. On the ENCOR 350-401 exam, this tests your understanding of Ansible connection plugins for network automation—a common trap is assuming a successful playbook run means the configuration was applied. Remember that for any ios_config or similar network module, you must explicitly declare `connection: network_cli` (or the fully qualified `ansible.netcommon.network_cli`) in your playbook. A helpful memory tip: “CLI for CLI”—if you’re sending CLI commands, use the network_cli connection.
350-401 Automation Practice Question
This 350-401 practice question tests your understanding of 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.
A network engineer is troubleshooting an Ansible playbook that uses the ios_config module to apply ACLs. The playbook runs without errors, but the ACLs are not applied to the device. The engineer verifies that the device is reachable and the credentials are correct. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The playbook is missing the connection parameter set to 'network_cli'
The ios_config module requires the connection parameter to be set to 'network_cli' (or 'ansible.netcommon.network_cli') to use the CLI transport for sending configuration commands to network devices. Without this, Ansible defaults to the 'smart' connection, which may not properly interact with network device CLIs, causing the playbook to run without errors but not apply the ACLs.
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.
✗
The device is in a different VRF and not reachable
Why it's wrong here
The engineer verified reachability.
✓
The playbook is missing the connection parameter set to 'network_cli'
Why this is correct
Ansible network modules require the connection: network_cli setting.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The ACL syntax in the playbook is incorrect
Why it's wrong here
Incorrect syntax would cause Ansible to report an error.
✗
The ios_config module requires the netmiko library to be installed on the control node
Why it's wrong here
The ios_config module uses its own SSH implementation, not Netmiko.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the misconception that Ansible modules automatically handle network device connections, but in reality, the 'connection: network_cli' parameter is mandatory for network modules to function correctly.
Detailed technical explanation
How to think about this question
The 'network_cli' connection plugin uses Paramiko (SSH) to establish a persistent CLI session, sending commands line by line and parsing responses. Without this, Ansible may use the 'local' connection, which runs modules on the control node without actually sending commands to the device, or the 'smart' connection, which may fail to negotiate the correct network device prompt. In real-world scenarios, forgetting the connection parameter is a common oversight when transitioning from Linux server automation to network automation.
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 security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 350-401 question in full detail.
Automation — This question tests Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The playbook is missing the connection parameter set to 'network_cli' — The ios_config module requires the connection parameter to be set to 'network_cli' (or 'ansible.netcommon.network_cli') to use the CLI transport for sending configuration commands to network devices. Without this, Ansible defaults to the 'smart' connection, which may not properly interact with network device CLIs, causing the playbook to run without errors but not apply the ACLs.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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