“How does one know if he lives in an illegal rental?”

“Dear PoPville,

How does one know if he lives in an illegal rental?

We rent the main and upstairs floors of a townhouse in DC with a separately rented basement unit. Searching PIVS on DC’s website, there is no certificate of occupancy or basic business license at the house.

Am I in an illegal rental? And if so, what rights or responsibilities do I have and what rights or responsibilities does my landlord have?”