F5CAB1 Install, Initial Configuration, and Upgrade Practice Question
An administrator is upgrading a BIG-IP from version 15.1 to 17.1. After the upgrade, the administrator notices that the device is not passing traffic and the TMOS logs show that the TMM process failed to start. Which action should the administrator take first to resolve the issue?
⚠ Common exam trap
The trap here is jumping to a rollback or reinstall without first diagnosing the TMM failure through logs, which could reveal a simple fix.
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
✓
Check the /var/log/ltm and /var/log/tmm logs for specific error messages related to the TMM failure.
When TMM fails to start after an upgrade, the first step is to examine the logs for specific errors. The logs in /var/log/ltm and /var/log/tmm provide detailed information that can pinpoint the cause, such as a configuration object that is incompatible with the new version. Based on the error, the administrator can decide whether to fix the configuration, apply a patch, or roll back.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
Check the /var/log/ltm and /var/log/tmm logs for specific error messages related to the TMM failure.
Why this is correct
The first step in troubleshooting a TMM startup failure is to examine the logs. The /var/log/ltm and /var/log/tmm files contain detailed error messages that can indicate the root cause, such as a misconfiguration, missing dependency, or software bug. This information is crucial to determine the appropriate fix, which could be a configuration change, patch, or rollback. Always gather logs before taking drastic actions.
- ✗
Reinstall the new software image using the tmsh command install sys software.
Why it's wrong here
Reinstalling the software image is a time-consuming step that may not address the underlying issue. The TMM failure could be due to a configuration problem or a bug that would persist after reinstallation. Before reinstalling, the administrator should analyze logs to identify the cause. Reinstallation should be considered only if the image is corrupted, which is less likely than a configuration or compatibility issue.
- ✗
Reboot the BIG-IP into the previous software volume and restore the UCS backup.
Why it's wrong here
While rebooting into the previous volume and restoring the UCS backup would revert the system, it is not the first action to take. The administrator should first investigate the TMM failure to understand the cause. If the issue is a simple configuration incompatibility, it might be fixable without a full rollback. However, if the TMM failure is due to a critical bug, rollback may be necessary. The first step is to check logs for specific errors.
- ✗
Disable the TMM process and restart the BIG-IP to allow traffic to flow using the host processor.
Why it's wrong here
The TMM (Traffic Management Microkernel) is responsible for processing traffic on the BIG-IP. Disabling it would prevent any traffic from being processed, as the host processor is not designed to handle data plane traffic. This action would not resolve the issue and would likely make the situation worse. The TMM must be running for the BIG-IP to function as a load balancer.
Visual reference
About these practice questions
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official F5 exam blueprint
This F5CAB1 practice question is part of Courseiva's free F5 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 F5CAB1 exam.