Blockchain Interview Questions with Answers, Tips for Cracking Interview in Blockchain admin, Blockchain developer and lightning

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  1. 1. What are blockchain requirements?_text]


    Blockchain is a truly disruptive technology that can transform business networks. We also believe that this innovation has to happen in the open, collaborating with other technology companies and industries. To this end, IBM continues to contribute code to the Hyperledger Project.(ibm blockchain interview questions)

    From IBM’s perspective, industrial-grade blockchain technologies have the following characteristics:

    A shared, permissioned ledger is the append-only system of record (SOR) and single source of truth. It is visible to all participating members of the business network.
    A consensus protocol agreed to by all participating members of the business network ensures that the ledger is updated only with network-verified transactions.
    Cryptography ensures tamper-proof security, authentication, and integrity of transactions.
    Smart contracts encapsulate participant terms of agreements for the business that takes place on the network; they are stored on the validating nodes in the blockchain and triggered by transactions.

    2. Is it possible to switch the data once it’s written in an exceeding block?_text]Answer:

    No, it’s impossible to do so. Just in case any modification is needed, the organization merely has to erase the knowledge from all different blocks too. Because of as a result of no different reason than this, knowledge must be given the acute care of while mistreatment this approach.

    3. What are Merkle trees? How vital are Merkle trees in Blockchains?_text]Answer:

    Merkle Tree additionally called ‘hash tree’ is a data structure in cryptography during which every leaf node could be a hash of a block of knowledge, and every non-leaf node could be a hash of its kid nodes.

    if somebody has to verify the existence of selected dealing in an exceedingly block, then he doesn’t need to transfer the complete block. Downloading a collection of a branch of this tree that contains these dealings is enough. We have a tendency to check the hashes we are simply rising the branch (relevant to my transaction). If these hashes consider sensible, then we all know that these specific dealings exist during this block.

    4. Name some widespread platforms for developing blockchain applications_text]Answer:

    After the event of bitcoin, numerous blockchain platforms started arising. Ethereum came right once the evolution of Bitcoins, and is one in all the favored public platforms for building Blockchain primarily based applications.

    Then there’s a Hyperledger community for building enterprise-based solutions. Also, Qtum, IOTA, EOS are a number of the widely used platforms for building Blockchain.

    5. What is geth’s “fast” sync, and why is it faster?_text]Answer:

    Instead of processing the entire blockchain one link at a time and replay all transactions that ever happened, fast sync downloads transaction receipts along with the blocks and pulls an entire recent state database.

    6. What is Remix?_text]Answer:

    An online tool for developing, testing and deloying contracts. It’s great for quickly building and testing lightweight contracts but not for more complex ones.

    7. What is a chain fork?_text]Answer:

    Blocks in the ledger are included in such a way as to build the longest chain, i.e., the chain with the greatest cumulative difficulty. Forking is a situation where there are two candidate blocks competing to form the longest blockchain and two miners discover a solution to the proof-of-work problem within a short period of time from each other. The network is then divided, because some nodes get blocks from miner #1 and some from miner #2. (ibm blockchain interview questions)

    A fork usually gets resolved in one block, because the probability that this situation happens again gets extremely lower with the next blocks that arise, so soon there is a new longest chain that will be considered as main.

    8. How is a block recognized within the Blockchain approach?_text]Answer:

    Every block during this online ledger essentially consists of a hash pointer that acts as a link to the block that is before it, transaction knowledge and in fact a stamp of time.

    9. Name the common sort of ledgers which will be thought of by users in Blockchain?_text]Answer:

    These are:

    • Centralized Distribution
    • Decentralized distribution
    • Distributed network
    • Follow the link to know more about Ledger

    10. Example of a Smart Contract use case?_text]Answer:

    A popular Seller-Buyer scenario where a Buyer deposits money in the smart contracts, Seller sees the deposit and sends the goods, Buyer receives the goods and releases the payment.

    11. Does gas price determine when a transaction is processed?_text]Answer:

    Yes and no. The higher the gas price, the more likely your transaction will be mined. Despite, gas price is not a guarantee for faster transaction processing.(The Best Blockchain Interview Questions And Answers (Updated 2018))

    12. What is the very first thing you must specify in a Solidity file?_text]Answer:

    The version of Solidity compiler, which is specified as ^0.4.8. It is necessary because it prevents incompatibility errors which can be introduced when compiling with another version.

    13. How DApps are different from Smart Contracts ?_text]


    dApps are a ‘blockchain enabled’ website, where the Smart Contract is what allows it to connect to the blockchain. The easiest way to understand this is to understand how traditional websites operate. (ibm blockchain interview questions)

    The traditional web application uses HTML, CSS and Javascript to render a page. It will also need to grab details from a database utilizing an API. When you go onto Facebook, the page will call an API to grab your personal data and display them on the page. Traditional websites:  Front End → API → Database
    dApps are similar to a conventional web application. The front end uses the exact same technology to render the page. The one critical difference is that instead of an API connecting to a Database, you have a Smart Contract connecting to a blockchain. dApp enabled website:  Front End → Smart Contract → Blockchain
    As opposed to traditional, centralized applications, where the backend code is running on centralized servers, dApps have their backend code running on a decentralized P2P network. Decentralized applications consist of the whole package, from backend to frontend. The smart contract is only one part of the dApp:

    Frontend (what you can see), and
    Backend (the logic in the background).
    A smart contract, on the other hand, consists only of the backend, and often only a small part of the whole dApp. That means if you want to create a decentralized application on a smart contract system, you have to combine several smart contracts.(Blockchain Training)