Blockchain Interview Questions & Answers (2025)

The blockchain is an incorruptible digital ledger technology in a centralized form. It is a collective database for the immutable records and it was discovered along with the invention of Bitcoin. It is an open source approach which works securely and provides long-term services. With the blockchain system, each and everyone gets equal opportunity to enhance and implement the technologies.

Blockchain has gained enough attention these days. The reason behind it is-

• It is an open source project and is absolutely compatible with other application.
• It is totally secure hence online transactions and rest of the things are safe.
• It is eligible for any of the business application.

The properties of blockchain comprise as -

• Decentralized system
• Distributed ledger
• Safe ecosystem
• Minting

For any of the online platform, security is always a priority. Encryption allows the user to keep the data safe. The encrypted code is encoded or manipulated to some extent before it reaches to a network by the sender and only the legal or authorized parties can access through the data. Encryption adds overall security to the blockchain.

When any of the value gets transferred from Bitcoin wallets then it gets deposited into blockchain. Bitcoin keeps the secret data or key which is used for the transactions and provide a calculated proof which belongs to the owner of the wallet.

There is no restriction while storing the data or records in the blockchain. Organizations use the blockchain for the security of the entire records. The broadly included ones are-

• Records for medical transactions
• Identity management
• Transaction process records
• Business transaction
• Documentation records

Bitcoin permits and enables the information which is to be distributed among the users without being actually copied. It is predominantly of three types:

• Public
• Consortium
• Private

The blockchain is actually a list of data or records which are stored as blocks. Each of these blocks is somehow related in connection to each other forming a chain like structure and overall it is called as blockchain technology. Each and every block is an online ledger which is having a hash pointer. These blocks are identified by the blog header hash and block height.

Each block and the entire blockchain is provided with enough security and secured by a tough cryptographic hash algorithm. Each of the blocks has a particular pointer and in case any manipulation is done with the constituent then it will change the hash identifier of the block. Thus, it offers an extreme level of protection and security in the blockchain.

Once a data is written in a block it is not possible to undo it. If the changes have to be done then in that case, the user has to delete the entire information from all of the blocks. Hence while modifying the data, extreme importance is given to the concepts and each and every segment.

The blockchain is eventually considered as incorruptible ledger is any of the ill-intentional personality acting solitary is powerless here. Augier says “to take control of the network any attacker have to control more than half of the total computing power”.

The major demarcation between both of them is that blockchain is a digital ledger which can be decentralized easily. On the other hand, the normal ledger is prepared by hands or manmade effort. The former one is performing all the tasks automatically hence the chances of error are extremely minimal. Later one is not up to the mark if it comes to errorless performance.

Multiple blockchain application development platforms emerged right after the development of Bitcoin. Ethereum is the most frequent one that evolved right after the discovery of Bitcoin. The second most popular public platform is hyper ledger community which helps to build up the enterprise based services. The list is followed by IOTA, EOS, Qtum and many more.

When a single token is spent a number of times as it consists of a digital file which can be cloned easily then it is called double spending. It is a depreciating situation which leads to the organisational level loss. The major purpose behind the security of this is to eradicate all such approach. The mechanism is such when any transaction is about to be done it is asked with multiple parties.

It is understood that the safe and secure transaction is certainly important with the online transactions. Secret sharing distinguishes the secret and personal information into various segments and sends it to the user through a network. The former information will only be shared when the user allows it to. Hence there are multilevel security and secret sharing in the blockchain.

On the basis of certain factors their differentiation is possible.

Hyperledger, a collaborative project of public blockchains and similar applications, commenced in 2015 by Linux Foundation and have collected contributions from IBM, Intel Corporation, and SAP Ariba, to promote the collaborative advancement of blockchain-related distributed ledgers and does not recommend bitcoin or any other cryptocurrency. However, the program is excited by blockchain technology. Blockchains will construct a new era of transactional applications that builds trust and transparency at their heart while streamlining industry processes and legal restrictions.

The nonce is the short form for Number Only Used Once is a number added to an encrypted block in a blockchain, which when rehashed, meets the difficulty level limitations. The nonce is the number that digital miners are solving for and when a solution is found, blockchain miners are awarded cryptocurrency in exchange. Once the scientific computations are interpreted by a miner, they are gifted cryptocurrency for their time and skill. The nonce is difficult to find and is considered a way to wipe out the less talented crypto miners.