6. Identify the Advantages of Common Design Patterns (MVC and Observer) 200-901 Practice Questions (Page 2)

Questions 6–10

1. 6expert · hard

   A network automation team is building a real-time dashboard that displays device status. The dashboard must update automatically when device status changes. The team also wants to add new dashboard widgets later without modifying the core status-monitoring code. The team is considering MVC and Observer patterns. Which approach best satisfies both requirements?

   • AUse MVC with the model implementing the Observer pattern to notify views of status changes
   • BUse MVC only, with the controller polling the model for changes
   • CUse Observer only, with the status as the subject and the dashboard as the observer
   • DUse Singleton for the status object and Factory for the widgets
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2. 7expert · hard

   A network automation team is building a configuration deployment tool. The tool has a web interface for engineers to initiate deployments and a REST API for CI/CD integration. The team wants to: (1) allow the deployment engine to notify both interfaces of deployment progress, (2) keep the deployment logic independent of the interfaces, and (3) ensure that adding a new interface (e.g., a mobile app) does not require changes to the deployment engine. Which pattern combination is the most appropriate?

   • AUse MVC to let the deployment engine notify the interfaces, and use Observer to separate the deployment logic from the interface controllers.
   • BUse MVC to separate the deployment logic from the interfaces, and have the interfaces poll the deployment engine for progress.
   • CUse Observer to let the deployment engine notify the interfaces, and use MVC to separate the deployment logic from the interface controllers.
   • DUse Observer to separate the deployment logic from the interfaces, and use MVC to ensure the deployment engine is a singleton.
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4. 8foundation · easy

   What is a primary advantage of the Observer pattern in a software system?

   • AIt requires that each observer be a subclass of the subject class.
   • BIt guarantees that the subject will never change its state after initialization.
   • CIt allows a subject to notify multiple observers of state changes without the subject knowing their details.
   • DIt ensures that all observers are tightly coupled to the subject for direct method calls.
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5. 9foundation · easy

   When comparing MVC and Observer patterns, which statement correctly identifies a key advantage of MVC over Observer?

   • AMVC provides a structured separation of concerns that makes the codebase easier to maintain and test.
   • BMVC ensures that the business logic is completely independent of the data storage.
   • CMVC allows multiple objects to be notified automatically when a subject changes.
   • DMVC guarantees that the application will have a single user interface.
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6. 10expert · hard

   A network automation team is redesigning a legacy configuration management tool. The tool currently has a single monolithic script that reads device configurations, parses them, and displays them in a CLI. The team needs to: (1) add a REST API and a web UI without duplicating parsing logic, (2) allow multiple internal services to react to configuration changes, and (3) minimize the risk of breaking existing CLI behavior. The team has limited time and cannot refactor the entire codebase at once. Which approach best satisfies these constraints?

   • AUse MVC to separate the view from the controller, and use Observer to let the model poll the REST API for changes.
   • BKeep the monolithic script but add a REST API wrapper that calls the same script, and use Observer to notify the web UI of changes.
   • CIntroduce MVC by separating the parsing logic into a model, and use Observer to notify the CLI, REST API, and web UI of changes.
   • DUse Observer to decouple the CLI from the parsing logic, and use MVC to allow the REST API to replace the CLI.
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