When upgrading to a newer TMOS software version, BIG-IP validates whether the current license is permitted to run that version.
This is controlled by the Service Check Date in the device’s license file.
If the Service Check Date is older than the minimum required for the target version:
The system boots into the new volume ,
But fails to load the configuration ,
And will instead present messages indicating that the configuration cannot be applied due to an invalid or outdated license .
This is a well-known behavior:
An outdated license, not reactivated before upgrade, causes configuration load failure after reboot into the new software.
Why the other options are incorrect:
A. Performed on the standby unit
Upgrading a standby unit does not cause configuration load failure.
Standby-only upgrades are standard best practice.
C. Two reboots required
BIG-IP does not require two reboots during an upgrade.
One reboot into the new volume is sufficient.
D. DNS connectivity failure
DNS connectivity does not affect configuration loading.
DNS is only needed for automatic license activation, not for applying config at boot.
Thus, the configuration failed to load because the license was not reactivated before the upgrade , making Option B correct.
