This questions comes up periodically, usually when customers want to run separate SCCM hierarchies in the same network or AD environment. There are issues with client assignment based on this scenario, but what about software distribution? Will the client think it's in a "fast" or "slow" boundary? Turns out that the client will always assume it's in a slow boundary if no site boundaries are defined. And, remember what the default action in the advertisement properties is for clients that are in a slow boundary? Do not run the program. So, be careful.