Rack System, Reptile Basics

I ordered a wide Iris MCB-S Rack and was wondering do people typically drill holes in the containers? Or is the airflow get in some other way?

Yes - you'll likely need to solder holes in the tubs. Since the Iris tubs (at least the ones I have) fit very snugly in these racks, I ended up needing to make a ton of holes in mine to get some airflow in there.

You can solder or drill holes. I've done both. I prefer to drill. I happened to have some brad point drill bits from a set. I found those work perfectly.

Soldering is generally the method most use, it's faster, the holes are not jagged or sharp, and there is less chance of cracking the tub. I tried drilling once with a nice new bit and still from the pressure of me pushing on the drill it cracked the tub. Just do your soldering outside or in a well ventilated area.