200-901 Infrastructure and Automation Practice Question
This 200-901 practice question tests your understanding of infrastructure and automation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 a network automation engineer at a large enterprise. The network consists of 200 Cisco Catalyst switches distributed across five data centers. Each switch runs IOS-XE and supports NETCONF. Your team uses a centralized Ansible control node to manage configurations. Recently, the security team mandated that all management access must use SSH keys instead of passwords. You updated the Ansible inventory to use SSH keys and tested on a few switches successfully. However, when you run the playbook against all switches, about 30 switches fail with the error: 'Authentication failed.' You verify that the SSH public key is correctly deployed on those switches via the console. What is the most likely cause of the failure?
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 private key file on the Ansible control node has permissions 644, which SSH rejects
SSH strictly requires private key files to have permissions no more permissive than 600 (owner read/write) or 640 (owner read/write, group read) on Unix-like systems. A permission of 644 allows group and others to read the key, which SSH interprets as insecure and refuses to use, causing 'Authentication failed' even though the public key is correctly deployed on the switches.
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 public key on the switches is not in the correct format
Why it's wrong here
The engineer verified the public key is correct via console.
✗
The Ansible become method is misconfigured
Why it's wrong here
Become is for privilege escalation, not SSH login.
✓
The private key file on the Ansible control node has permissions 644, which SSH rejects
Why this is correct
SSH requires private key permissions to be 600 or more restrictive.
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 switches are not reachable over the network
Why it's wrong here
The error is authentication, not connectivity.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the subtle distinction between SSH key format issues and file permission issues, where candidates assume the problem is key format when the real issue is the private key file's restrictive permissions required by OpenSSH.
Detailed technical explanation
How to think about this question
OpenSSH enforces strict permissions on private key files (typically ~/.ssh/id_rsa) to prevent unauthorized access; if permissions are too open (e.g., 644), ssh exits with 'Permissions 0644 for 'key' are too open.' and refuses to use the key. This is a common pitfall when copying keys between systems or using configuration management tools that inadvertently change file permissions. In Ansible, the private key is specified via the ansible_ssh_private_key_file variable or the --private-key CLI option, and the control node's SSH client enforces this check before any connection attempt.
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 200-901 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.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Infrastructure and Automation — This question tests Infrastructure and Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The private key file on the Ansible control node has permissions 644, which SSH rejects — SSH strictly requires private key files to have permissions no more permissive than 600 (owner read/write) or 640 (owner read/write, group read) on Unix-like systems. A permission of 644 allows group and others to read the key, which SSH interprets as insecure and refuses to use, causing 'Authentication failed' even though the public key is correctly deployed on the switches.
What should I do if I get this 200-901 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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Question Discussion
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