Cambridge Technicals in IT - Unit 02 - LO5.2

What is the purpose of a Data Flow Diagram (DFD)?

• To display the physical layout of a database.
• To illustrate an organisation’s hierarchy.
• To describe programming logic.
• To show how data flows through a system.

Answer explanation

A DFD visually represents the flow of data through a system, showing how inputs are processed and stored.

Which of the following is a component of a DFD?

• Database schema.
• Programming syntax.
• External entities.
• Network topology.

Answer explanation

External entities represent sources or destinations of data within a DFD.

What is an external entity in a DFD?

• A symbol representing network connections.
• A process that modifies data.
• A person, organisation, or system that interacts with the DFD.
• A data storage location.

Answer explanation

External entities are people or systems outside the DFD that send or receive data.

In a DFD, what is a process responsible for?

• Representing external entities.
• Controlling user access to the system.
• Storing data permanently.
• Transforming input data into output data.

Answer explanation

A process modifies, manipulates, or transforms data within the system.

What does a data store represent in a DFD?

• The movement of data between entities.
• A temporary or permanent storage of data.
• A processing action performed on data.
• A connection between two entities.

Answer explanation

Data stores represent locations where data is held, such as databases or files.

Which symbol is commonly used to represent a process in a DFD?

• A rectangle.
• A triangle.
• A circle or rounded rectangle.
• A diamond.

Answer explanation

Processes are typically represented by circles or rounded rectangles in a DFD.

How does data flow in a DFD?

• Only from external entities to processes.
• In any direction without restrictions.
• Only from processes to data stores.
• In one direction only.

Answer explanation

Data flows in one direction in a DFD, representing how information moves through the system.

What must every data flow in a DFD include?

• A reference to the system’s database schema.
• A connection to at least one process.
• A direct link to a data store.
• A security classification label.

Answer explanation

Every data flow must connect to at least one process to ensure proper system representation.

What is a Level 0 DFD also known as?

• A network topology diagram.
• A use case diagram.
• A context diagram.
• A process diagram.

Answer explanation

A Level 0 DFD, also called a context diagram, provides a high-level overview of the system.

How does a Level 1 DFD differ from a Level 0 DFD?

• It is used only for small systems.
• It includes more detailed sub-processes.
• It eliminates external entities.
• It only focuses on database storage.

Answer explanation

A Level 1 DFD breaks down processes into more detailed sub-processes.