Top Blockchain Interview Questions

Blockchain technology is a new buzzword for confidentiality, integrity, and availability of digital transactions. You definitely heard of digital cryptocurrency called Bitcoin, which is based on the blockchain. Here, we will discuss questions which can be asked in the technical interview of the blockchain.

Q. What is a Blockchain?

Ans: Blockchain is a technology helps in peer to peer transfer of digital information and assets without any middleman or intermediaries. Blockchain relied on immutable records of the distributed database. Currently, blockchain technology is using in many application such as finance, manufacturing, public distribution, healthcare, and other sectors.

Q. What is Bitcoin?

Ans: A person or a group of person, Satoshi Nakamoto, introduced a new digital currency called bitcoin which is based on the blockchain technology. Bitcoin enables people to transfer money anonymously from one point to another without any central authority (decentralized network).


Q. As there is no central authority in case of digital currency called Bitcoin, then how did Bitcoin realize trust and security among people?

Ans: Bitcoin implements a software program based on blockchain which helps in validating, verifying and build consensus in a new infrastructure for transferring of digital currency. Creation of every transaction in an immutable ledger is the basic building block of trust and security in blockchain infrastructure.

Q. What is a smart contract?

Ans: A smart contract is a software code and is a part of the blockchain node. Execution of smart code depends on the message which embeds in the transaction. It is used to provide conditional operations for execution of transactions.

Q. Which language used to write the smart contract?

Ans: Solidity is a high-level language which can be used to write the smart contract and compiled into bytecode.

Q. What is the basic structure of blockchain?

Ans: Transaction is the basic structure of blockchain. Later, the same transaction is validated and broadcast in an immutable ledger. Many transactions form a box and many boxes form a chain through a digital data link.


Q. What is Unspent Transaction Output (UTXO)?

Ans: UTXO is used as an input in a new transaction. It contains the following information:

  • unique identifier of the transaction that created the UTXO
  • Index of this UTXO in the transaction’s output list
  • Value
  • Optional: conditions under which output can be spent

Q. What are the advantages of blockchain technology?

Ans: Advantages:

  1. It helps in building trust among unknown people by ensuring CIA triad ie. confidentiality, integrity and availability.
  2. Create logs of the transaction in an immutable ledger.
  3. Able to send and receive money without any centralized authority (e.g. bitcoin).

Q. What is Ethereum blockchain?

Ans: Ethereum blockchain is considered as a mother of all blockchain. In 2013, Ethereum founders introduced a framework for code execution and are based on the concept of Smart contracts.

Q. Is there any difference between Bitcoin Stack and Ethereum Stack?

Ans: Yes, usage of smart contracts are the major difference between Bitcoin Stack and Ethereum Stack.

Q. What are the types of Blockchain network.

Ans: Blockchain network can be categorized into 3 types

(a) Public blockchains: This type of network can be accessed by the general public and make transactions. Bitcoin and Ethereum are two popular public blockchains.

(b) Private blockchains: As the name indicates, the only person which are allowed by network administrators able to participated and make transactions.

(c) Consortium blockchains: It is considered as the semi-decentralized network. Here, similar to the private blockchain, also required permission of network administrator but it is controlled by many companies which operate each node on such a network.

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Disclaimer: This tutorial is for educational purpose only. Individual is solely responsible for any illegal act.


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