Mock Exam Flashcards
Status Code 401
Indicates authentication error. Often due to incorrect details.
Example - username error
Status Code 404
Indicates that the requested resource could not be found on the server
200 OK Status Code
Indicates request was successful, and data loads as expected.
Example - Data loaded successfully
Encryption
Used to secure data within a smart contract
Which technology provides security for secure transactions?
Blockchain
When promoting the reliability of a DApps system, which feature would reassure a stakeholder with security concerns?
Answer - No single point of failure.
Definition - In DApps, no single point of failure ensures that if one component fails, the others can continue operating, improving reliability
What is the purpose of a ‘contract registry’ within a distributed application framework?
A contract registry is a list of all deployed smart contracts in a system, allowing easy reference and validation.
Example - contract registry might be used to ensure the correct version of a smart contract is being accessed by clients
Which cloud deployment model would be most appropriate for ensuring data security while still leveraging cloud resources?
Hybrid Cloud.
Hybrid Cloud combines public and private cloud resources, providing a balance of security and scalability
Which term refers to the concept of distributing computing resources as close to the source of data as possible?
Edge Computing.
Edge computing brings data processing closer to the source, reducing latency and improving efficiency.
Which technology would allow for automating the process of deploying, scaling, and managing containerised applications?
Docker.
Docker automates container deployment and management, making it easier to scale and manage applications
In a RESTful API, what is the purpose of the HTTP DELETE method?
Remove an existing resource - DELETE is used to remove resources on a server.
What does the term ‘latency’ refer to in a distributed network?
The time delay in transmitting data across the network
Which tool could be used to visually monitor and manage containerised applications?
Kubernetes Dashboard
What does the term ‘smart contract’ imply in the context of blockchain applications?
A smart contract is an agreement coded into the blockchain that automatically enforces the terms, ensuring the data integrity and protection
API Rate Limiting
Restricts the number of API requests a user can make within a given timeframe
Which characteristic is essential to consider in designing a distributed application for high availability?
Multiple instances across different locations
Explain the concept of ‘Service-Oriented Architecture’ (SOA) and its impact on distributed application design.
SOA - architectural style that enables different services to communicate over a network.
Impacts distributed applications by allowing modular, reusable services that can be independently maintained, enhancing flexibility and scalability.
Summarise the process for testing a smart contract and the steps to take before releasing it.
- Compilation.
- Writing test cases for each function and possible scenarios using Mocha Chai Framework.
- Running automated tests using tools like Truffle or Hardhat.
- Conducting security audits to identify vulnerabilities.
- Deploying on a testnet before launching on the main network to check for issues.
Define and describe how ‘gas’ operates within the blockchain system to manage transaction fees.
Gas refers to the fees required to execute transactions on the blockchain.
Each operation has a gas cost, and users pay based on the computational resources they consume, ensuring fair usage and network stability.
Illustrate how an IT team could benefit from an ‘Address Book’ within their system.
Address Book - stores user or contract addresses in a smart contract environment.
Could be used to manage and retrieve contract addresses efficiently, improving usability.
Describe how REST APIs could support smart contracts.
REST APIs - provide a way for external systems to interact with smart contracts, enabling functions like querying contract states or sending transactions.
This facilitates seamless integration with other applications.
What are the potential downsides to decentralising a database?
- Increased complexity in data consistency and coordination.
- Higher costs due to resource redundancy.
- Security concerns with open data access, requiring robust access control.
Outline the key steps in compiling a smart contract for deployment.
- Writing the smart contract code in Solidity or another language.
- Using a compiler like solc to convert the code into bytecode.
- Deploying the bytecode to a blockchain, where it can be executed.
Which reference model be adopted to explain interactions within distributed applications?
CORBA (Common Object Request Broker Architecture).
Helps distributed apps interact seamlessly.
What type of agreement would be most appropriate to ensure data protection and integrity?
Smart Contract.
Smart contract is an agreement coded into the blockchain that automatically enforces the terms, ensuring data integrity and protection.
What are the resource allocation regions in Azure commonly called?
Regions.
These are the designated geographic areas where resources are deployed and allocated.
Which term describes older systems where services are centralised on a single server without division?
Monolithic.
A monolithic system is one where all components are interconnected within a single service, unlike a distributed system.
To ensure transaction history, what encoding method does Ethereum use for storing strings?
Hexadecimal.
Ethereum stores data in hexadecimal format to ensure compatibility and data security within its blockchain.
How does decentralisation in DApps lead to claims of ‘no downtime’?
A different node can continue if one fails - Decentralisation allows another node to take over if one goes down, which helps achieve zero downtime.
When compiling smart contracts, which of these file types would Truffle be unable to recognise?
Which two data formats are most commonly recognised in web services for APIs?
JSON and XML.
Commonly used data formats for APIs due to their structured and standardised formats.
When using distributed applications, which of the following describes the concept of ‘horizontal scaling’?
Adding more servers to distribute the load.
Horizontal scaling means increasing system capacity by adding more servers, rather than upgrading a single server.
Which API method would be most suitable for retrieving data from a server without modifying it?
The GET method
In the context of cloud services, what does ‘IaaS’ stand for?
Infrastructure as a service
What does the term ‘immutable’ mean in the context of blockchain?
Transactions cannot be altered (changed or deleted) once added.
When creating a distributed application, what is the main benefit of using microservices?
Allows each component to be developed independently.
This is efficient and scalable.
Which protocol is most commonly used for secure transactions over a distributed application?
HTTPS (HyperText Transfer Protocol Secure)
API Response Methods commonly used in smart contracts
HttpResponseMessage - Returns detailed HTTP responses, ideal for sending status codes and messages.
IHttpActionResult - An abstract layer that simplifies creating various HTTP responses.
HttpResponseResult - A flexible response that can be used in smart contracts to send dynamic messages.
Write the following API data in both JSON and XML formats:
Company Data: Report Title: Vehicles, Staff: 334, Cars: 226
Category: Diesel - 180, Petrol - 45, Electric - 37, Other - 14
Discuss how blockchain transactions might be integrated within a company’s systems.
Blockchain transactions can provide verifiable records for the company’s operations.
Integrations could involve using a blockchain API to query and update transaction data securely.
Explain the importance of Git for version control and how a company might benefit from it.
Git tracks code changes, allowing for rollback and collaborative development.
A company would benefit from using Git to manage smart contract code, ensuring version consistency and audit trails.
Describe the primary features of an eWallet and how it enables users to perform secure transactions.
eWallet stores digital funds and allows users to transact.
Features include - unique address, balance tracking, transaction history, and security features like encryption and 2FA.
Explain CAP theory and how it applies to a company’s distributed system model, providing examples.
CAP (Consistency, Availability, Partition Tolerance) theory states that a distributed system can only achieve 2 of these 3 aspects at any time.
A company’s system could prioritise availability and partition tolerance to handle a high volume of requests.
List and discuss the key issues a company might face when transitions to a decentralised system architecture.
Challenges include managing data consistency, handling complex coordination, ensuring adequate security, and managing resource allocation efficiently.
Describe the concept of ‘no single point of failure’ and why it is beneficial for distributed systems.
DApps are designed so that if one component fails, others can continue to operate. This design enhances reliability and minimises downtime.
Describe how a company could use encryption to protect user data and transactions in a distributed app environment.
Encryption ensures that sensitive data remains protected when stored or transmitted.
A company could implement encryption to safeguard transaction data in its distributed app.
What advantages do distributed apps have over centralised apps in terms of scalability?
DApps scale well by adding more nodes to the network, enabling the system to handle larger loads and more users without compromising performance.
Explain how a contract registry might be utilised within a company’s systems, and provide a suitable use case.
A contract registry is a record of all deployed contracts, allowing easy access and updates.
A company might use it to ensure clients and interacting with the correct versions of contracts.
Provide a detailed comparison of JSON and XML data formats, focusing on their suitability for API data transfer.
JSON - lightweight, easy to read, commonly used for data transfer in web apps.
XML - while more verbose, supports metadata and is suited for complex data hierarchies.
JSON is often preferred in APIs for its efficiency.
Describe how the role of decentralisation in DApps can prevent downtime. Provide and example scenario.
In a decentralised DApp, tasks are distributed across multiple nodes. If one fails, others can continue, ensuring uptime.
For example, a company could rely on multiple nodes to provide continuous service even if one server goes down.
