Top 12 Interview Questions for Blockchain Developers

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This article was published as a part of the Data Science Blogathon.

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Blockchain is becoming the new trend of our technological age. It is growing rapidly and creating a sensation in the market. Industry experts are putting their heart and core into growing the graph of blockchain-based products. As a result, the number of opportunities for developers doubles or triples. So, if you want to be successful in your blockchain interview, you can check out this blog. lets start!

interview questions

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Q1: What do you understand by Blockchain technology?


Blockchain is a software protocol which consists of many pieces like databases, software applications, many connected PCs etc. and cannot run without internet. In simple words, Blockchain is a technology that is used to securely transfer important items like contracts, assets, money etc. without the intervention of any third party intermediary like government or bank.

As data is entered inside a blockchain, it becomes difficult to manipulate, which is why blockchain is called a secure technology.

Q2: What is a block in a blockchain, and how can one identify it?

A block in the blockchain is nothing but a secure permanent record of the transaction. A blockchain consists of a list of records that are stored in blocks. Block acts as a container for the blockchain and holds transaction data. As soon as a transaction is added to a block, it cannot be reversed, similarly, when a block is added to the blockchain, it becomes irreversible.

To store transaction records securely, blocks require certain elements such as a version of the block, hash of the previous block, etc., which are stored in the header hash. So, the block header hash and block height are the fields used to identify a block, and a cryptographic algorithm, namely the hash function, is used to locate the data inside the block. This hash function takes the entire data of the block and modifies it into a unique string of symbols which is considered as the ID of the block.

Q3: Explain the different types of blockchain.

There are three types of blockchain:

Top 55 Blockchain Interview Questions and Answers in 2022 |  adureka


1. Public Blockchain

A public blockchain is a permissionless blockchain that can be accessed by any user on the Internet. It is an open source public ledger that can be read, written and audited by anyone. Examples could be bitcoin and ethereum.

2. Private Blockchain

A private blockchain is a proprietary blockchain owned by an authorized organization. Users on the Internet can view the personal ledger but cannot verify it.

An example might be Blockstack.

3. Consortium Blockchain or Federated Blockchain

A federated blockchain is a type of blockchain where the consensus process is controlled by a specific node (a group of companies called a consortium).

An example could be Ripple.

Q4: What are the famous platforms for developing blockchain applications?

Some famous blockchain platforms:

1. Ethereum

2. Wave

3. Quantity

4. Hyperledger Sawtooth

5. Quorum


7. R3 cord

Q5: What kind of records can we keep in the blockchain? Are there any restrictions on the type of records?

We can use blockchain to store any type of records such as bank statements, Instagram chats, medical reports, pictures, etc. Blockchain does not create any limits i.e. there is no restriction on storing documents in the blockchain. Some examples of documents that can be stored on the blockchain are:

1. Identity Management

2. Transaction Processing

3. Records of Medical Transactions

4. Organizations Related Programs

5. Documentation

Q6: Name some famous cryptocurrencies.

The most popular cryptocurrencies include:

1. Bitcoin

2. Bitcoin Cash

3. Litecoin

4. Ethereum

5. Wave

Q7: Why is blockchain a reliable approach?

Below are some of the reasons why blockchain is considered a reliable approach:

1. Blockchain is a highly encrypted, secure and hacking-proof technology.

2. Blockchain is designed for online transactions, so developers pay more attention to security.

3. Blockchain is an open-source technology that is highly compatible with various business applications.

4. Blockchain can be easily considered irrespective of the type of business/company owned.

5. Blockchain has no additional or central authority to control it.

6. All transactions in the Blockchain are irreversible, which means that we cannot change any transaction after a successful entry into the Blockchain.

Q8: What do you understand by encryption and its role in blockchain?

Encryption is nothing but a technology that ensures data security for organizations. Any type of data can be encoded in encryption before it is sent out over the network and can only be decoded by the receiver with the decrypted key. This makes blockchain technology more stable by increasing the security and validity of blocks.

In blockchain, encryption obscures and secures data, networks, and systems to ensure that no unauthorized party can gain access to the data. This prevents incidents of data loss or hacking.

Q9: What do you mean by 51% attack in blockchain?

A 51% attack, also known as a double-spend attack, refers to a miner or group of miners who charge more than 50% of the network’s hashing capacity, mining hash rate, or processing power on a blockchain system. try to do.

An In-depth Guide to 51% Attacks in Cryptocurrency


These attackers can prevent new transactions from being verified and eliminate payments between uses. They are also able to double spend coins by reversing verified transactions when the network is in control.

Q10: Define the term double spend. Is it possible to spend twice as much on blockchain technology?

Double spending is nothing but a potential flaw in the digital cash scheme, which occurs when the same digital token, which is made up of digital files that can be easily cloned, is used multiple times. The purpose of the blockchain is to eliminate double spending for multiple parties to authenticate the transaction before it is written to the ledger(s).

Q11: What factors are taken into account for transaction data security in blockchain?

Blockchain is nothing but a chain or list of digital records (blocks) of transactions that are linked before and after. This chain is an obstacle for hackers because of tampering with a record. They have to replace the entire block containing multiple records and its associated blocks; Otherwise they will be easily caught. That’s why blockchain is considered a highly secure technology. Many factors contribute to the security of transactional data. Some are:

Cryptography:- Blockchain uses cryptography to protect the record of transactions and the identity of the user with the help of hash function.

Key Concept:- Public and private keys are used for data encryption or decryption in blockchain. The private key acts as a personal digital signature for the user.

Q12: Explain the major advantages of Blockchain technology.

The advantages of blockchain technology are mentioned below:

Enhanced Security- Blockchain provides highly advanced protection to critical and sensitive data as compared to various record-keeping systems. To prevent fraud and unauthorized activities, it uses end-to-end data encryption. Instead of storing information on a single server, it uses multiple networks so that no hacker can access or view the data.

Improved Traceability- Blockchain technology allows instant traceability. An audit trail is created by the blockchain, which records the emergence of assets at every stage of their journey to prevent fraud.

Cost-Saving- With the help of blockchain, organizations save a lot of money as it is a cheap technology, and they do not have to pay extra amount to third party vendors.


Blockchain is a very trending technology which opens the door to success for developers in this domain. Many companies like IBM, Accenture, Capgemini etc provide opportunities to blockchain developers. In this blog, we discussed the most frequently asked questions in Blockchain Interview.

The key insights are:

1. What is Blockchain, its types, and what platforms can we use to develop Blockchain applications?

2. We have seen what kind of records we can store in the blockchain.

3. We also discussed why blockchain is a reliable approach and how it keeps transaction data secure.

4. We also briefly discussed about 51% attack and double spend in blockchain.

5. Lastly, we discussed some of the benefits of this technique.

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