Which of the following is the MOST widely used operating system on multiprocessing server systems?

A.
Windows XP

B.
Windows NT

C.
UNIX

D.
OS/2

Explanation:
In a multiprocessing system, the operating system is responsible for allocating resources to competing processes in a controlled environment. Most modern network operating systems are capable of this function, including Windows NT, Windows 2000, Windows XP, UNIX and IBM’s OS/2. However, because of it’s stability, UNIX is the most widely used.
Incorrect Answers:
A: Windows NT is capable of multiprocessing but its instability hindered the wide spread usage of this operating system.
B: Windows XP is capable of multiprocessing and is widely, however, this operating system is used for workstations rather than servers.
D: OS/2 is capable of multiprocessing but its usage has been limited to IBM systems.
References:
Charles J. Brooks, Server+ Certification Exam Cram 2 (Exam SK0-002), QUE Publishing, Indianapolis, 2006, pp. 62-64.