Hardware Reliability and Bathtub Curve
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Questions and Answers

Which phase of the bathtub curve is characterized by a constant failure rate?

  • Normal operating phase (correct)
  • Wear-out phase
  • Burn-in phase
  • Infant mortality phase

    • What is the primary cause of failures during the wear-out phase?

  • Aging or wear-out mechanisms (correct)
  • Human error
  • Poor design or manufacturing defects
  • Random failures

    • Which of the following is not a phase of the bathtub curve?

  • Wear-out phase
  • Burn-in phase (correct)
  • Normal operating phase
  • Infant mortality phase

    • What is the primary goal of exception handling?

    <p>To handle unexpected events</p> Signup and view all the answers

    Which software quality model is not mentioned among the options?

    <p>CMM model</p> Signup and view all the answers

    What is MTTF an abbreviation for?

    <p>Mean time to failure</p> Signup and view all the answers

    How many product quality factors are proposed in McCall quality model?

    <p>8</p> Signup and view all the answers

    What is the 'Useful Life' phase of the 'bathtub curve' characterized by?

    <p>Constant failure rate</p> Signup and view all the answers

    What is software reliability defined as?

    <p>Time to failure</p> Signup and view all the answers

    Time Behavior and Resource Behavior fall under which quality attribute of ISO 9126?

    <p>Efficiency</p> Signup and view all the answers

    How are reliability and failure intensity related?

    <p>Direct relation</p> Signup and view all the answers

    What is the main goal of combining historical data and systematic techniques in software project estimation?

    <p>To improve estimation accuracy</p> Signup and view all the answers

    Who is responsible for designing security into a system?

    <p>System designers</p> Signup and view all the answers

    What is the main benefit of using diverse technologies in distributed systems?

    <p>Increased system availability</p> Signup and view all the answers

    What is social engineering in the context of system security?

    <p>A way to fool accredited users into giving away secret information</p> Signup and view all the answers

    Why is it difficult to protect against social engineering in large organizations?

    <p>Due to the hierarchical structure and lack of personal relationships</p> Signup and view all the answers

    What is infrastructure security engineering responsible for?

    <p>Configuring existing infrastructure to conform to security policies</p> Signup and view all the answers

    What is the goal of application security engineering?

    <p>To design security into a system</p> Signup and view all the answers

    What is the main advantage of distributing assets in a distributed system?

    <p>Increased system availability</p> Signup and view all the answers

    What is the primary focus of configuration management policies and processes?

    <p>Recording and processing proposed system changes</p> Signup and view all the answers

    What is the purpose of process analysis in process improvement?

    <p>To identify process weaknesses and bottlenecks</p> Signup and view all the answers

    What is the relationship between the attribute that can be measured and the external quality attribute?

    <p>Dependent</p> Signup and view all the answers

    What is the most significant factor that affects the accuracy and efficacy of estimates?

    <p>Project size</p> Signup and view all the answers

    What describes the data and control to be processed?

    <p>Software scope</p> Signup and view all the answers

    What is the approach to requirements gathering that encourages the creation of a joint team of customers and developers?

    <p>FAST</p> Signup and view all the answers

    What is the primary objective of configuration management?

    <p>To record and process proposed system changes</p> Signup and view all the answers

    What is the outcome of process analysis in process improvement?

    <p>Identification of process weaknesses and bottlenecks</p> Signup and view all the answers

    What is the primary goal of the resistance strategy in enhancing system survivability?

    <p>To prevent attacks from being successful in the first place</p> Signup and view all the answers

    Why might you recommend against software reuse in critical applications?

    <p>Because source code may not be available for review and testing</p> Signup and view all the answers

    What is a potential risk of using COTS components?

    <p>Incompatible event/data model with other systems</p> Signup and view all the answers

    What is the primary goal of the recognition strategy in enhancing system survivability?

    <p>To recognize attacks as they occur and respond quickly</p> Signup and view all the answers

    In what circumstances might you recommend against software reuse?

    <p>When the business status of the code provider is dubious</p> Signup and view all the answers

    What is the primary goal of the recovery strategy in enhancing system survivability?

    <p>To quickly recover from successful attacks and restore normal system service</p> Signup and view all the answers

    What is a potential risk of using COTS components?

    <p>Inadequate performance when integrated with other systems</p> Signup and view all the answers

    Why might you recommend against software reuse in systems where performance is critical?

    <p>Because specially developed code can be made more efficient</p> Signup and view all the answers

    What is the main reason why it is practically impossible to validate reliability specifications when these are expressed in terms of a very small number of failures over the total lifetime of a system?

    <p>The number of failures is so low that it would take an unrealistically large amount of time to gather statistically valid failure data</p> Signup and view all the answers

    Which of the following is a circumstance where software reuse is not recommended?

    <p>In small systems where the costs of reuse are comparable to the savings</p> Signup and view all the answers

    What is a potential additional cost that may arise when deploying software as a service?

    <p>Increased maintenance costs</p> Signup and view all the answers

    What is the main distinction between application security engineering and infrastructure security engineering?

    <p>Application security engineering focuses on securing applications, while infrastructure security engineering focuses on securing the underlying infrastructure</p> Signup and view all the answers

    Why might a reliable system be unsafe?

    <p>Because a system can be reliable but still have safety vulnerabilities</p> Signup and view all the answers

    In what type of system would software reuse not be recommended, even if source code is available?

    <p>High-performance systems</p> Signup and view all the answers

    Why might deploying software as a service reduce IT support costs for a company?

    <p>Because it reduces the need for IT support</p> Signup and view all the answers

    Study Notes

    Bathtub Curve Phases

    • The infant mortality phase is characterized by a high initial failure rate.
    • The primary cause of failures during the infant mortality phase is defects in materials or manufacturing.

    Constant Failure Rate Phase

    • The constant failure rate phase is characterized by a constant failure rate.

    Wear-Out Phase

    • The primary cause of failures during the wear-out phase is deterioration due to aging.

    Non-Phases of the Bathtub Curve

    • There is no "random failure phase" in the bathtub curve.

    Exception Handling

    • Exception handling is a type of forward error recovery mechanism.

    Software Quality Models

    • ISO 9000 is not a software quality model.
    • McCall model and Boehm model are software quality models.

    Reliability

    • MTTF stands for Mean Time To Failure.
    • Reliability is defined as the ability of a system to perform its required functions under stated conditions for a specified period of time.
    • Reliability and failure intensity are inversely related.

    CMM Model

    • CMM (Capability Maturity Model) is a technique to improve the software process.

    Security

    • Configuration management policies and processes define how to record and process proposed system changes.
    • An independent relationship must not exist between the attribute that can be measured and the external quality attribute.
    • Social engineering is when accredited users of a system are fooled into giving away secret information.
    • It is difficult to protect against social engineering in large organizations because of their hierarchical structure and size.

    Estimation

    • Project size is an important factor that can affect the accuracy and efficacy of estimates.
    • Software scope describes the data and control to be processed.
    • Facilitated Application Specification Techniques (FAST) is a team-oriented approach to requirements gathering.

    Application and Infrastructure Security Engineering

    • Application security engineering is the responsibility of system designers who design security into the system.
    • Infrastructure security engineering is the responsibility of system managers or administrators who configure the existing infrastructure software.

    Diversity in Distributed Systems

    • Diverse technologies provide protection against common vulnerabilities in different elements of the distributed system.
    • Distributing assets so that attacks on one element do not disable the entire system enhances availability.

    Survivability Strategies

    • Resistance involves built-in mechanisms to resist attacks.
    • Recognition involves recognizing that an attack is underway.
    • Recovery involves built-in features to support recovery and resume normal system service quickly after a successful attack.

    Software Reuse

    • Software reuse is not recommended in certain circumstances, including:
      • If the business status of the code provider is dubious.
      • In critical applications where source code is not available.
      • In small systems where the costs of reuse are comparable to the savings.
      • In systems where performance is a critical requirement.

    COTS Risks

    • Risks that can arise when systems are constructed using COTS include:
      • Vendor risks (e.g., failure of vendor to provide support).
      • Product risks (e.g., incompatibility with other systems).

    Reliability and Safety

    • A reliable system can still be unsafe, and vice versa.
    • It is practically impossible to validate reliability specifications when these are expressed in terms of a very small number of failures over the total lifetime of a system.

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    Description

    Test your knowledge of hardware reliability and the bathtub curve, a concept that describes the failure rate of a product over time.

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