Blockchain Interview Questions

Preface – This post is part of the Blockchain Basics series.


Blockchain is a concept that has a list of records called blocks that store data publicly and in chronological order. In Blockchain, the Cryptography methodology is used to encrypt the information or data to ensure the privacy of the user.

Blockchain is a combination of the following three important technologies:

  • Cryptographic keys
  • Peer-to-peer network
  • Digital ledger

The various features of blockchain are:

  1. A public distributed ledger works use hashing encryption to encrypt information
  2. Every block within the blockchain has a hash value (generated everytime before the block is added), which is the digital signature of the block

The most common uses of Blockchain are:

  • Original content creation
  • Real-time IoT operating system
  • Voting mechanism
  • Supply chain and logistics monitoring

Blockchain is a technology emerging daily, and choosing a career in this field is a very good decision. In this blog, we will provide you most frequently asked questions related to blockchain in technical interview rounds. The industry experts repeatedly ask these questions of Top-notch companies.

General Blockchain Interview Questions

  1. What do you know about blockchain?
  2. Explain the difference between Bitcoin blockchain and Ethereum blockchain.
  3. Explain the main principle of blockchain technology.
  4. What are the various types of blockchains?
  5. What are the main reasons for considering Blockchain a trusted approach?
  6. Name the types of records present in the blockchain database.
  7. Is there any difference lies in between block records and transactional records?
  8. What type of database is used by Blockchain?
  9. Explain the features/properties of Blockchain.
  10. Explain Encryption. What is the role of encryption in blockchain?
  11. What do you understand by blocks in blockchain technology?
  12. How will you recognize a block in a blockchain approach?
  13. Is it possible to modify the data once written in a block?
  14. Explain Block Identifiers.
  15. Can we remove one or more blocks from the network of blockchain?
  16. What do you know about the security of a block?
  17. Explain Merkle trees. What is the importance of Merkle trees in Blockchains?
  18. What is a ledger?
  19. Is Blockchain an incorruptible ledger?
  20. Name some common types of ledgers that users in blockchain consider.
  21. How is a blockchain ledger different from an ordinary one?
  22. What types of records are kept in a blockchain?
  23. What are the common types of records that are kept in the blockchain?
  24. What does the system rely upon when a distributed digital ledger is used to record blockchain transactions?
  25. Explain the components of the Blockchain Ecosystem.
  26. Highlight some differences between proof-of-work and proof-of-stake.
  27. Name some popular platforms that are used for developing blockchain applications.
  28. Explain Double spending.
  29. Is it possible for a user to double spend in a Blockchain system?
  30. Explain some benefits of Blockchain.
  31. What does a block of blockchain consists of?
  32. Name the first distributed blockchain implementation.
  33. Bitcoin belongs to which type of Blockchain?
  34. How can we store Blockchain as a flat file, a database, or both?
  35. How are blocks linked in a blockchain?
  36. What is the primary benefit of immutability?
  37. Is a block in the blockchain possible to have more than one parent?
  38. What is the result of blockchain forks?
  39. Name one symmetric encryption algorithm.
  40. Explain decentralized network in the blockchain.

Advanced level Blockchain Interview Questions

  1. Name some widely used cryptographic algorithms.
  2. Explain the RSA algorithm and highlight the security of this algorithm.
  3. Highlight some significance of the blind signature.
  4. What is secret sharing?
  5. Explain off-chain transactions.
  6. What do you know about executive accounting?
  7. What are the threats to the information with which users are familiar?
  8. What will be your approach in handling the risk management when it comes to securing the transaction records?
  9. Does secret sharing have any benefit in blockchain technology?
  10. Does Blockchain support executive accounting?
  11. What do you understand by 51% attack?
  12. What are the various challenges an organization faces due to information leaks?
  13. Explain information processing according to you.
  14. What are the key challenges associated with information processing?
  15. What are the core requirements for a business Blockchain?
  16. Name the principles of Blockchain that help eliminate security threats.
  17. Explain security policy.
  18. List some of the popular consensus algorithms.
  19. Name the steps that must be followed in the Blockchain project implementation.
  20. What is the need for different consensus mechanisms?
  21. Explain a real-life use-case example where Blockchain is being used.
  22. What is the Genesis Block?
  23. Explain the purpose of the Blockchain node.
  24. Why does Blockchain need coins or tokens?
  25. What is the reason behind a fixed supply of bitcoins?
  26. How do verifiers check if a block is valid or not?
  27. Explain Decentralised application.
  28. Define a smart contract.
  29. Explain the trapdoor function.
  30. What is the importance of the trapdoor function in blockchain development?
  31. Explain mining difficulty.
  32. Explain what a target hash is.
  33. Define stealth address.
  34. Compare PoW and PoS.
  35. Is it possible to brute force bitcoin address creation to steal money?
  36. Explain Double spending.
  37. Define smart contracts and their applications.
  38. Where do nodes run a smart contract code?
  39. Name the very first thing you must specify in a Solidity file.
  40. Explain the term ‘Nonce’ and how it is used in mining.
  41. What do you understand about Coinbase transactions?
  42. What do you think about the future of blockchain?
  43. List some demerits of Blockchain.
  44. Explain the use of cryptographic algorithms in blockchain with the help of an example.
  45. Which cloud computing platform is used for hosting an enterprise blockchain network?
  46. Give one example of a smart contract verification tool.
  47. Explain “Gas” on Ethereum.
  48. Explain how you will deploy and develop an Ethereum smart contract using the Ethereum ecosystem tools.
  49. Explain how you will deploy Ethereum smart contract on Hyperledger Fabric.
  50. How will you create a blockchain application using Node.js?
  51. Make some comparisons between ScriptPubKey and P2SH addresses.
  52. Compare and contrast centralized, decentralized, and distributed ledgers.



  • Barry Allen

    A Full Stack Developer with 10+ years of experience in different domain including SAP, Blockchain, AI and Web Development.

    View all posts


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