FREE Blockchain Developer Decentralized Application (dApp) Architecture Questions and Answers

Question 1

A development team is building a dApp where the frontend is hosted on a decentralized storage network to maximize censorship resistance.
However, they notice that large media files are loading slowly for users.
Which of the following is the most direct and common architectural component used to address this issue in a decentralized manner without resorting to a centralized server?

Accepted Answer

Integrating a decentralized storage solution specifically designed for resilient and incentivized data delivery, such as Swarm or IPFS with Filecoin.

Answer

Implementing a Content Delivery Network (CDN) that pulls from a centralized cache.

Answer

Using a decentralized indexing solution like The Graph to query data more efficiently.

Answer

Increasing the gas price for transactions that load media files to prioritize them on the blockchain.

Question 2

In a typical dApp architecture, what is the primary role of a JavaScript library like ethers.js or web3.js?

Accepted Answer

To act as a bridge, translating frontend JavaScript calls into JSON-RPC requests that can be understood by an Ethereum node.

Answer

To execute smart contract logic directly within the user's browser, replacing the need for an EVM.

Answer

To provide a user-friendly interface for writing and debugging Solidity smart contracts.

Answer

To secure the user's private keys by storing them in the browser's local storage.

Question 3

A team is designing a dApp for a high-frequency trading game where thousands of interactions per second must occur between a small, defined group of players. Placing every interaction on the main Ethereum network would be prohibitively expensive and slow. Which architectural solution is best suited for this scenario?

Accepted Answer

A state channel, because it allows participants to conduct numerous off-chain transactions privately and settle only the final state on-chain.

Answer

A sidechain, because it runs a separate blockchain in parallel with its own consensus mechanism.

Answer

A Layer 1 scaling solution that involves sharding the main blockchain.

Answer

A centralized backend server to process all game interactions before batching them to the mainnet.

Question 4

Which of the following BEST describes the architectural difference between a dApp's backend and a traditional web application's backend?

Accepted Answer

A dApp's backend logic is encapsulated in smart contracts that run on a decentralized peer-to-peer network, whereas a traditional backend runs on centralized servers. [19, 22]

Answer

A dApp's backend runs on a centralized server managed by the development team, while a traditional backend is peer-to-peer.

Answer

There is no functional difference; both architectures rely on APIs to communicate with a centralized database.

Answer

A dApp's backend is written exclusively in JavaScript, while a traditional backend can use various languages like Python or Java.

Question 5

A developer is building a dApp that needs to display a user's transaction history. Querying the blockchain directly for every page load is inefficient and slow. Which architectural component should be integrated to improve performance for reading and presenting on-chain data?

Accepted Answer

An off-chain indexing service like The Graph.

Answer

A decentralized storage system like IPFS.

Answer

A wallet extension like MetaMask.

Answer

A layer 2 rollup solution like Optimism.

Question 6

When designing a dApp, a developer decides to store user profile pictures and other large static assets on IPFS. What is the primary architectural reason for this decision?

Accepted Answer

To reduce transaction costs and avoid bloating the blockchain with large amounts of data.

Answer

To ensure the assets can be modified and updated easily by any user.

Answer

To guarantee 100% uptime and data availability through a centralized pinning service.

Answer

To execute complex computations on the image data using IPFS's built-in virtual machine.