what's the difference between ip domain-name, vtp domain, and domain-name in dhcp pools? and should I use the same domain name for all three, or not (which is best practice)?
can't anyone be confused with these and ask someone? (would've preferred getting 0 in a homework than going to the trouble of asking in a forum for an answer)
The things you are asking about is not things you would encounter as any standard home user. Thus you are either configuring commercial grade equipment (likely cisco) or this is a homework quesiton.
So it comes down to either this is hoemwork, or you are attempting to configure cisco router with no training in cisco (and possibly no training in advanced networking concepts).