F5CAB1 Install, Initial Configuration, and Upgrade Practice Question
An administrator is upgrading a BIG-IP from version 14.1 to 17.1. The administrator wants to ensure that the upgrade does not fail due to insufficient disk space. Which command should be used to check the available disk space on the BIG-IP before the upgrade?
⚠ Common exam trap
The trap here is assuming that a tmsh command exists for checking disk space, when in fact standard Linux commands are used.
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
✓
df -h
Before upgrading a BIG-IP, it is critical to verify sufficient disk space. The 'df -h' command, run from the bash shell, provides a clear view of available space on all file systems. If any partition is nearly full, the upgrade may fail. The administrator should ensure there is enough free space, typically by removing old software images or log files. This command is the standard way to check disk usage on Linux-based systems like TMOS.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
show /system disk-usage
Why it's wrong here
This is not a valid tmsh command. The correct tmsh command to view disk usage is not available; administrators typically use 'df -h' from the bash shell. Using an invalid command will not provide the necessary information and could waste time. The upgrade process itself may check disk space, but it's best to verify manually.
- ✗
tmsh show sys disk
Why it's wrong here
The 'tmsh show sys disk' command does not exist in TMOS. While tmsh has many show commands, disk space is typically checked using standard Linux commands like 'df' or 'du'. Using an invalid command will result in an error and not provide the needed information. The administrator should use 'df -h' from the bash shell.
- ✓
df -h
Why this is correct
The 'df -h' command displays disk space usage in a human-readable format. It shows the available space on all mounted file systems, including the partitions used by TMOS. Checking this before an upgrade is essential to ensure there is enough space for the new software image and configuration. Insufficient space is a common cause of upgrade failures.
- ✗
ls -l /var/log
Why it's wrong here
The 'ls -l /var/log' command lists files in the /var/log directory, but it does not show disk space usage. It only shows file sizes and permissions. While log files can consume space, this command does not give a summary of available disk space. It is not the correct tool to check overall disk space before an upgrade.
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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.