Which functional groups are not reduced by DIBAL.H?
DIBAL-H does the following:

Acid chlorides to aldehydes (Fast)
$3^\circ$ amides to aldehydes
Nitriles to aldehydes
Ketones to $2^\circ$ alcohols
Aldehydes to $1^\circ$ alcohols. (Slower)

Also, it works best in these solvents: THF, toluene.
We need to avoid solvents like alcohols, amines, strong acids and halogenated compounds.