Even if it happens to be cross-platform. That's why Active Directory is based on LDAP, Kerberos, MAPI and other industry standards. But because Active Directory insists on controlling down to the network protocols, it will play nice only on a network where it's the master and all other directory servers and services are slaves. If you chat with system administrators or surf the Windows chat boards online, you come across consistent complaints about how hard it is to get Microsoft's Kerberos to work right. You also hear about the nightmare you'll face if you try to install Active Directory when your domain name server happens to run on Linux, Solaris, NetWare or anything else.
Horror stories abound.
No one talks about SNA much these days. Coincidentally, not many people are doing much with Active Directory these days either. Although Microsoft announced last week that it will reach the 1 million mark this month for Windows 2000 server licenses, the company is uncharacteristically modest about how many Active Directory installations it has so far. Like IBM's grand vision of SNA, Active Directory is a simple, monolithic answer to a complex, heterogeneous problem. So far, most users think it's the wrong answer.