Maximum number of RIDs
Someone asked today what the max RIDs allocated can be ...
Answer is: 2^30 or 1,073,741,824
Not sure if this is directly addressed in a KB but https://www.microsoft.com/technet/prodtechnol/comm/comm2002/maintain/perform/sadcs/ad02d.mspx has some interesting info around this area and other "Considerations for Internet Scalability" under the HKLM\SYSTEM\CurrentControlSet\Services\NTDS\RID Values
spat