We purchased a second home for our sons to live in at college. we visit. we also rent to 2 other people. what type of rental property is this classified as?

Do you collect rent from the other 2  persons? Are you paying a mortgage? YOu may be able to claim the interest paid (there are rules and limits). Do you have and have tracked repair and maintenance expenses? If so, I would think it is a NORMAL rental property. Do you stay there when visiting your sons? If so, it could be termed a vacation home to also rent to others.  

If this is merely a cost sharing arrangement where the amount paid is below fair market rental, there would be no reportable income to you. If the “rent” amount is fair market value, or more, there is still some question as to whether you even have to report it, as it almost always comes out zero. Most people take the attitude that it is not income; it's just room mates sharing expenses and ignore it. Family, as opposed to unrelated roommates, makes that position stronger.

Here’s what you may be required to do:

Report the income (enter at Rents & Royalties/Income & expenses from Rental Properties); and then deduct the expenses on schedule E. If the room mate has full run of the house, and there's just the 2 of you, then half your expenses are deductible (mortgage interest, property taxes, insurance, utilities, repairs, and depreciation [if needed}). Your net income will usually be less than zero.

What you are NOT allowed to do, because it is your own home (you have "personal use") is claim a loss from this activity, to offset other income. Because of the "personal use rule", your deductions are limited to your income. Net effect ZERO.