How does the allylic halide behave under SN2 and SN1 conditions? Briefly explain why the allylic halide should be able to undergo both SN2 and SN1 mechanisms.

Question

If this is any relevant to the question, we did an experiment on the SN1/SN2 reactivity of alkyl halides, using NaI in acetone mixture and AgNO3 in ethanol mixture for SN2 and SN1 reactions respectively. These were the halides used:
1-bromobutane
1-chlorobutane
bromocyclohexane
2-chlorobutane
2-bromobutane
2-chloro-2-methylpropane
2-bromo-2-methylpropane
1-chloro-2-butene
bromocyclopentane