Inspecting Rentals (apartments, condos...)

Okay, just so you know I did a little bit of searching on Google before posting this likely elementary question. I am certified in Alaska to perform residential existing homes only. Are apartments, condos, duplexes, etc. considered commercial or residential properties?
Thank you in advance for the help!
Jason

An individual unit (a condo, a townhome, etc) is residential.

An entire building up to 4 units is considered residential.

Inspecting a building that has more than 4 units or any commercial space in it is considered a commercial property.