SDLC Interview Questions and Answers

Ques 36. Explain when to use the Incremental model.

The incremental model should only be used when:

• The requirements of the complete system are clearly defined and understood.
• Major requirements must be defined; however, some details can evolve with time.
• There is a need to get a product to the market early.
• New technology is being used
• Resources with needed skill sets are not available
• There are some high-risk features and goals. 

Ques 37. Describe spiral software development life cycle model.

The spiral SDLC model combines components of both design and prototype in phases. It’s a hybrid of waterfall and prototyping model. One should use spiral SDLC model for large and expensive projects. 

Ques 38. Briefly describe the phases in the Spiral model.

Phases in spiral model:

a) System requirements are identified in detail.
b) An initial design is created for the new system based on the requirements in previous phase. All feasible and technical approaches are identified and analyzed to build the system. The design is done on a very broader and deeper scope to identify and deal with potential risks in the system.
c) A prototype is created depicting a few features of the system.
d) A second prototype is created using 4 steps: Evaluate first prototype, define requirements for second prototype, planning and designing for second prototype, constructing and testing second prototype.

Ques 39. Explain the strengths of the spiral model.

Strengths of the Spiral model:

a) Early identification of potential risk areas.
b) Customer sees a prototype very early in the SDLC.
c) Critical and risky features are built first for risk mitigation and clarifying requirements.
d) Design can evolve with iterations.
e) Feedback from users helps maintain their expectations.
f) Cost is assessed frequently, hence better planning. 

Ques 40. Explain the weaknesses of the spiral model.

Weaknesses of Spiral model are:
a) Not suitable for smaller or low budget projects as cost is high for identifying risks.
b) Time spent on risks, planning, and prototyping may not be as efficient.
c) It is complex.
d) Spiral may continue indefinitely.
e) Hard to define clear milestones, which allow the SDLC to move to the next phase.
f) Developers must have other work during non development phases.