6. Identify the Advantages of Common Design Patterns (MVC and Observer) 200-901 Practice Questions (Page 1)

Questions 1–5

1. 1expert · hard

   A team is developing a configuration management tool. The tool has a web UI and a REST API. Both must use the same validation logic. The team also wants to add new validation rules later without changing the UI or API code. Which pattern should they use?

   • AFactory pattern, to create validation objects for each interface
   • BSingleton pattern, to ensure one instance of the validation logic
   • CObserver pattern, with the UI and API observing the validation logic
   • DMVC pattern, with the validation logic in the model and the UI and API as views
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2. 2foundation · easy

   Which benefit is directly associated with the Observer pattern's support for broadcast communication?

   • AThe subject must be a singleton to ensure only one observer exists.
   • BObservers must poll the subject continuously to check for changes.
   • CA single state change in the subject can automatically update all interested observers.
   • DThe subject can only communicate with one observer at a time.
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4. 3foundation · easy

   In which scenario would the Observer pattern be more appropriate than the MVC pattern?

   • AWhen the application needs to support multiple user interfaces for the same data.
   • BWhen the application requires a single controller to handle all user input.
   • CWhen multiple components need to react automatically to changes in another component's state.
   • DWhen the application requires a clear separation between the user interface and business logic.
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5. 4application · medium

   A team is building a web application that displays real-time network statistics. The backend collects metrics and the frontend updates charts automatically when new data arrives. The team also wants to add new chart types later without changing the backend. Which combination of patterns best meets these requirements?

   • ASingleton for the metrics and Factory for the charts
   • BObserver only, with the metrics as the subject and the charts as observers
   • CMVC with the model using the Observer pattern to notify views of changes
   • DMVC only, with the metrics as the model and the charts as the view
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6. 5expert · hard

   A network automation team is building a system that monitors device status and sends alerts. The system must support multiple alert channels (email, SMS, webhook) and allow new channels to be added later without modifying the monitoring code. Which pattern should they use?

   • AMVC pattern, with the device status as the model and the alert channels as views
   • BObserver pattern, with the device status as the subject and the alert channels as observers
   • CSingleton pattern, to ensure one instance of the monitoring code
   • DFactory pattern, to create alert objects for each channel
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