Blockchain is among the fastest-growing and most dynamic technologies in the world that presents various research and job possibilities in renowned companies around the globe. So becoming a Certified Blockchain Expert is a reliable path for a candidate looking to secure career growth. As the demand for experts in Blockchain technologies grows day by day and new jobs, sprout up in the area, and as the demand for Blockchain training courses rises day by day, it is essential to know how to plan for a Blockchain technology interview to get their dream job as a Certified Blockchain Expert. Hence, here we have provided answers to some of the most commonly occurring interview questions on Blockchain Technology to help you to ace your next tech interview.
Basic Level Blockchain Interview Questions
1. Define Public Blockchain
A Public blockchain, By definition, is an open-source, decentralized, and shared public record from which anyone can access data and analyze it. They are created to be Permissionless blockchains that are free to use.
2. Define Distributed Ledger Technology
A distributed ledger technology (DLT) is a decentralized database maintained by various participants. An account of all the new transactions in the ledger gets attached to each participant’s ledger.
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3. Define Ethereum (ETH)
Ethereum is a free open-source software program designed on the basis of Blockchain technology. It allows developers to organize and expand decentralized applications that are not constrained by any separate entity.
4. Tell us Some Benefits of Blockchain Technology
The principal benefits of blockchain technology are:
- Security: The activities are highly protected as they are encrypted.
- Immutability: Various records are generated and collected from a single block via the peer-to-peer interface. So it is very hard to modify something in the block.
- Transparency & Resiliency: Every activity is collected over a distributed network enabling everyone to observe them, and making blockchain translucent and resilient.
5. Describe a Blockchain Explorer
Blockchain explorer is a software piece that extracts data from a blockchain making use of an API and a blockchain node. It then mimics a database to create the data and then grants the user access to the data in a searchable form.
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Blockchain Interview Questions – Intermediate Level
6. How is the Hash (Block Signature) Generated?
The complete process of generating a block signature involves the following steps:
- Passing the transaction details through a one-way hash function, namely, SHA-256.
- Then running the output value through the signature algorithm (like ECDSA) using the user’s private key.
- The encrypted hash, along with other relevant information (like the hashing algorithm), is called the digital signature.
7. List Down Some of the Most Extensively Used Cryptographic Algorithms
Here are a few of the most popular algorithms:
- SHA – 256
- Triple DES
- Blowfish
- RSA (Rivest-Shamir-Adleman)
- Ethash
8. Define a Smart Contract, and List Some of its Applications
A Smart contract is a self-executing contract that contains the terms and conditions of an agreement between multiple peers
Some common applications of a smart contract are:
- Transportations: Goods shipment can be easily tracked using smart contracts
- Protecting copyrighted content: Often, smart contracts are used to protect ownership rights for music or books
iii. Insurance: Smart contracts are useful to identify false claims and prevent forgeries
- Employment contract: Smart contracts are helpful in facilitating the payment of wages
9. Define the Ethereum Network. List the Ethereum Networks you know.
Ethereum is a blockchain-based distributed computing platform that features smart contract functionality which in turn enables users to create and deploy their own decentralized applications
The three types of networks in Ethereum are:
- Live network/main network – Smart contracts are deployed on the main network
- Private networks – These networks are not connected to the main network. Instead, they run within the organization’s premises despite carrying similar features of an Ethereum network.
- Test network (e.g: Ropsten, Kovan, Rinkeby) – These networks allow users to run their own smart contracts without any fees before they are deployed on the main network.
10. What is a Dapp? How is it Different from a Normal Application?
- A Dapp is a decentralized application deployed using a smart contract
- The back-end code (smart contract) of a Dapp runs on a decentralized peer-to-peer network
- The process:
- Front-end
- Smart contract/backend code
- Blockchain (P2P contract)
- A normal application, on the other hand, has a back-end code running on a centralized server
- It is merely a computer software application hosted on a central server
- The process:
- Front-end
- API
- Database – runs on the server
Blockchain Interview Questions – Expert Level
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11. List the Steps that are involved in a Blockchain Project Implementation
Requirement identification:
- Identify the problem and goal
- Identify the most suitable consensus mechanism
- Identify the most suitable platform
- Account for implementation and deployment costs
Planning stage:
- In this stage, an individual evaluates all requirements and decides on a suitable blockchain platform to be implemented.
Development and implementation of a project:
- Designing the architecture
- Designing the user interface
- Building the APIs
Controlling and monitoring the project:
- Applying Proof of Concept (POC)
- Identifying and fixing issues
12. Differentiate Between Proof of Work vs. Proof of Stake.
Proof of Work (PoW):
PoW in Blockchain is the process of solving a complex mathematical puzzle through a process called mining. The probability of mining a block depends on the amount of computational work performed by the miner. A typical miner spends a lot of computing power and hardware to solve the cryptographic puzzle.
Proof of Stake (PoS):
On the other hand, PoS is an alternative process to PoW, which involves the Blockchain achieving distributed consensus. Here, the probability of validating a block depends upon the number of tokens owned by the miner. The more tokens a miner has, the more their chances of getting a block validated. It was created to minimize the use of expensive resources spent for mining.
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13. What is a 51% Attack?
A 51% attack in Blockchain refers to a vulnerability in which an individual or group of people holds control of the majority of the mining power/hash rate. This lets attackers prevent new transactions from getting confirmed. Later, they can double-spend these coins. In a typical 51% attack, smaller cryptocurrencies are the ones that are attacked.
14. Define Function Modifiers in Solidity. List the Most Widely Used Modifiers.
Function modifiers in Solidity are used to modify the behavior of smart contract functions easily. In other words, it can be used to build additional features or for applying restrictions on the function of smart contracts. The most commonly used function modifiers in solidity are given below:
- View – These are functions that cannot modify the current state of a smart contract because they are read-only functions.
- Pure – These are functions that can neither read nor write the current state of a smart contract. Instead, they return the same result given by their input values.
