I think DOS 5 and higher has built in CD-ROM drivers. As for networking in DOS it's not so much the drivers but the networking suite you choose such as LAN manager, Novell Netware or MS network client. There are also others such as WATT32 and such. As for "RAM" drivers they're not needed unless you have some special memory expand board.
If you want a modernish TCP stack in DOS you want to use WATT32 for the sake of memory and CPU usage, it also uses small Packet drivers. You could use MS network client 3.0 but it's a memory hog and uses NDIS drivers.
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DOS is so minimalistic and old, there might not be any infrastructure/drivers for what you want.
Well, which DOS driver you're looking for?
This might be an interesting site for TO.
For networking, the suite matters, and that will affect what drivers you need. (packet or NDIS/ODI?)
If you want hardware driver you need a hardware driver, usually supplied. Now the CDROMS etc are on the IDE bus, so that is not an issue.
Most of the time, DOS is unconnected.