How old is really old?
The Azure Data Lake Store binaries have been broadly certified for Hadoop distributions after 3.0 and above. We are really in uncharted territory for lower versions. So the farther away you go from 3.0 the higher the likelihood of them not working. My personal recommendation is to go no lower than 2.6. After that your mileage may really vary.
This is a good article, and do check it out. A very small mini-rant follows: Hadoop version 2.6 is not old. Nor is 2.7. 2.7 is the most recent production-worthy branch and 3.0 isn’t expected to go GA until August.