One change control function that is required in client/server environments, but is not required in mainframe environments, is to ensure that:

The fundamental difference between mainframe and client/server architectures dictates unique control requirements. In a centralized mainframe environment, the application resides in a single location. In a distributed client/server environment, application components exist on both the central server and numerous client workstations. Consequently, a critical change control function is to ensure that the software versions on all client machines are updated and synchronized with the server-side application. This prevents compatibility issues, data corruption, and functional errors that can arise from version mismatches across the network. This synchronization challenge is not present in a mainframe environment where users access a single, centrally managed program.

B. Emergency move procedures are documented and followed. This is a fundamental control for managing urgent changes in any IT environment, including both mainframe and client/server, to maintain stability and auditability.

C. Appropriate users are involved in program change testing. User Acceptance Testing (UAT) is a standard and essential part of the change management process regardless of the underlying system architecture.

D. Movement from the test library to the production library is controlled. This control, ensuring only authorized and tested code is promoted to the live environment, is a cornerstone of change management in both centralized and distributed systems.

1. The Institute of Internal Auditors (IIA)

GTAG 1: Information Technology Controls

2nd Edition

2012. Page 16 states

"In a distributed environment

it is important to ensure that the correct versions of software are on all the appropriate machines. This is not an issue in a centralized environment." This directly confirms that version synchronization is a specific concern for distributed (client/server) systems.

2. Weber

R.

Information Systems Control and Audit

Pearson

2011. Chapter 12

"Controlling Systems Development and Maintenance

" discusses how the distribution of processing in client/server systems introduces control risks

such as inconsistent program versions on client machines

that are not prevalent in centralized mainframe architectures.

3. Vaassen

E. H. J.

Meuwissen

R. H. G.

& Schelleman

C.

Accounting Information Systems and Internal Control

John Wiley & Sons

2009. The text differentiates controls for centralized versus decentralized systems

highlighting that in decentralized (client/server) models

ensuring consistency and integrity of software across multiple nodes is a key control objective not present in the same way in centralized (mainframe) systems.