Blockchain Developer Decentralized Application Architecture 2

Question 1

In a typical dApp architecture, what is the primary role of the smart contract layer?

Accepted Answer

Encoding and enforcing the application's business logic and state transitions

Answer

Storing large media files on-chain

Answer

Rendering the user interface

Answer

Managing DNS resolution

Question 2

Why do most dApps store large files on IPFS or Arweave rather than directly on-chain?

Accepted Answer

On-chain storage is extremely expensive per byte and bloats the chain

Answer

On-chain storage is free but slow

Answer

IPFS guarantees instant global consensus

Answer

Smart contracts cannot reference external hashes

Question 3

What does a 'content-addressed' storage system like IPFS use as a file identifier?

Accepted Answer

A cryptographic hash of the content (CID)

Answer

A sequential database ID

Answer

The file's owner address

Answer

A randomly assigned UUID

Question 4

Which component lets a browser-based dApp frontend submit transactions signed by the user?

Accepted Answer

A wallet provider injecting an Ethereum provider object

Answer

The block explorer API

Answer

A centralized payment gateway

Answer

The IPFS gateway

Question 5

What is the main purpose of an indexing layer such as The Graph in a dApp stack?

Accepted Answer

To efficiently query and serve historical/aggregated on-chain data

Answer

To execute smart contract code

Answer

To store private keys securely

Answer

To replace the consensus algorithm

Question 6

In dApp architecture, what is a 'node provider' such as Infura or Alchemy responsible for?

Accepted Answer

Providing RPC access to blockchain nodes so apps avoid running their own

Answer

Signing user transactions automatically

Answer

Hosting the dApp's HTML and CSS

Answer

Generating new private keys for users

Question 7

Why is the frontend of most dApps still typically hosted on conventional or decentralized web hosting rather than on-chain?

Accepted Answer

Serving UI assets on-chain would be prohibitively expensive and slow

Answer

Smart contracts cannot store any data

Answer

Browsers cannot read blockchain data

Answer

It is legally prohibited