Distributed Data Processing (DDP): which of the following is NOT a common system configuration/topology used in DDP?

Introduction / Context:
Distributed Data Processing (DDP) systems can be arranged using various network topologies that define how nodes connect and communicate. Knowing which terms denote topologies versus other system properties helps avoid confusion in design discussions and exam settings.

Given Data / Assumptions:

• We distinguish network topology names from processing modes.
• Star, ring, tree, and bus are standard topology terms.
• “Realtime” describes timing constraints, not a physical or logical interconnection pattern.

Concept / Approach:
A configuration/topology specifies node-to-node connection geometry. Star centers on a hub; ring connects nodes in a closed loop; bus uses a shared backbone; tree is a hierarchy of branches. “Realtime” refers to systems that must respond within deterministic time bounds, which can be implemented on any of these topologies. Therefore, “realtime” is not a configuration.

Step-by-Step Solution:

Verification / Alternative check:
Networking texts categorize topologies separately from timing/processing styles, confirming this distinction.

Why Other Options Are Wrong:
Star/ring/tree/bus are canonical topologies widely used in distributed systems.

Common Pitfalls:
Mixing performance or timing requirements with topology terms; they are orthogonal design dimensions.

Final Answer:
realtime