here is the case and see if some one can help me.
our network comprises of 400 work stations and 1721 router for internal routing and 2501 for external routing. we are having 3 domains and 3 respective domain controllers. so each workstations connects to there respective domain controller on there logins. and this all workstations are located from floor 1 to floor 10 of the building. and its not obvious that the computers belong to one floor belongs to the same domain say "ABC-CO.COM" there is a possibility that few users may belong to other domains also. our LAN is connected by Dlink unmanaged gigabit switches. by having an uplink from every floor to the server room. now the problem is we want to segment our network with a single Switch (2950) by using vlan to their respective domain. and we are using DHCP server too. so do u think tht taking an uplink of the floor and plugging it in the manageable switch in server room and assigning them to the vlan is feasible with a single switch.