Blockchain interview questions & answers | Cryptography, Ethereum, Solidity

Blockchain is the latest buzzword in the market. When Bitcoins were introduced, there was tremendous excitement about the underlying technology. Innovators and investors poured in funds as they recognized how lucrative blockchain technology would be. The blockchain industry is vibrant, and new products and applications are introduced daily. These blockchain interview questions will help you get industry-ready and ace your interview.

Blockchain developer skills

Blockchain developers manage the complete lifecycle of blockchain applications. They are accountable for the research and implementation of the application. They design the system architecture, generate smart contracts, and improve the protocols. To handle these responsibilities blockchain developers need to develop and master certain skills. Here are some blockchain developer skills you require to manage blockchain development effectively.

• Cryptography – Cryptography is the method of protecting and securing information and communication by using code, so it is accessed by the intended audience. As a blockchain developer, you need to use cryptography and must be familiar with the concepts. 
• Smart contracts – Ethereum introduced smart contracts. It has since been used in most blockchain solutions. Blockchain developers need to familiarize themselves with the concept of smart contracts. It is now considered to be an essential skill. Developers use specific languages like Chaincode and Viper for smart contracts. You can expect some questions on smart contracts in your blockchain interview questions.
• Data Structure – As a blockchain developer, you need to be well-versed in the basics of data structure. The data structure is the foundation of any blockchain. You need to be well-versed in the concepts to become a blockchain developer. 
• Blockchain architecture – you need to be familiar with the three types of blockchain architecture – consortium, private, and public architecture.

Also read: Solana vs Ethereum | A Comparative study of top 2 blockchains

General blockchain interview questions

Blockchain technology is at a nascent stage and it ideal time to enter it as a developer. If you are planning to start a blockchain career, you need to focus on acquiring the required skills and certifications. In this blog, we focus on general blockchain interview questions that are common during blockchain developer interviews.

1. How does blockchain work?

Blockchain is a combination of 

• Cryptography keys 
• a peer-to-peer network containing a shared ledger, 
• Method of computation that stores and record network transaction

When a new transaction is entered into the blockchain. The transaction is transmitted to a network of peer-to-peer computers scattered all over the world. The network of computers mathematically solves the equations to confirm the validity of the transaction. A block is created after the transaction is confirmed. These blocks are chained together to create a history of all the transactions, thus creating a permanent record. The blockchain transaction is complete.

2. How two blocks of blockchain are related to each other?

According to Wikipedia, a blockchain is “a distributed database that maintains a continuously expanding list of ordered records, called blocks,” which are “connected using encryption. Each block includes transaction information, a timestamp, and a cryptographic hash of the one before it. A blockchain is a decentralized, distributed, and open digital ledger that is utilized to log transactions across numerous computers in a way that prevents the record from being changed retrospectively without changing all succeeding blocks and obtaining network consent.

3. What is mining?

Mining is the process of adding transactions to the distributed ledger in a blockchain. Though the term is primarily associated with Bitcoin, other blockchain technologies also use mining. Bitcoin miners who run mining operations are rewarded with Bitcoins. Miners create a hash of transactions that are difficult to counterfeit thereby maintaining the integrity of the blockchain without requiring a central system. Mining requires a powerful CPU, has higher electricity requirements, and generates more heat than a normal computer, it is often done with a specialized computer.

Also read:  How to mint an NFT on Solana? | Step by step guide

4. What does a ledger in the blockchain do?

A public ledger refers to the ancient method of maintaining records that was used to track news, analysis, and prices of agricultural commodities. The ledger was available for general viewing and verification. The ledger in the blockchain keeps track of each participant’s anonymous identity, their balance, and the history of legitimate transactions executed between the network participants. The public ledger is available for general viewing and verification. Ledger. There is no central authority or viewer that can view the details of the participants, participants thus maintaining complete privacy.

5. Which set of features of blockchain ensures business network trust?

Features of blockchain ensure business network trust is – 

• Immutable – Blockchain networks are permanent and cannot be altered. 
• Distributed – All members within the network have a copy of the ledger ensuring complete transparency.
• The decentralized – blockchain network is decentralized or there is no governing authority to make decisions or oversea them
• Secure – All the records are individually encrypted. 
• Consensus – Every blockchain has a consensus to assist the network in reaching choices quickly and impartially.
• Unanimous – All members have to agree to the validity of the record before they can be added to the network.
• Faster Settlement – When compared to the conventional banking system, blockchain has a faster settlement.

6. How do smart contracts work? Name a few smart contract platforms you have used.

Contractual parties need to finalize the terms and conditions of the contract. After finalization, the terms and conditions of the contract are translated into a code. the code contains a variety of conditional statements that outline several circumstances for a potential future transaction. t is copied across the blockchain’s users and saved in the network. The required transaction is carried out if a condition of the contract is met and has been confirmed by every user of the blockchain network. Some of the smart contract platforms I have used are –

• Ethereum
• Hyperledger Fabric
• NEM
• Stellar
• Waves

Also read: Cryptocurrency Consultant | How to become a genius cryptocurrency consultant and 10 best career paths?

Cryptography interview questions

As we mentioned before, cryptography is the building block of the blockchain. As a blockchain developer, you should have a clear understanding of how cryptography works. In this section, we focus on cryptography interview questions that can be asked of blockchain developers. These questions can be used by businesses when they want to hire a developer on a full-time or contract basis.

1. What is cryptography?

Cryptography is the process of securing data and preventing illegal access. Cryptography is employed in the blockchain to safeguard transactions between two nodes in a blockchain network. The two main ideas in a blockchain are cryptography and hashing. In a P2P network, messages are encrypted using cryptography, and a blockchain’s block information and link blocks are secured using hashing. Cryptography focuses on the security of participants, transactions, and precautions against double-spending. It safeguards blockchain network transactions. It ensures that only authorized people can read, acquire and handle the data. 

2. What are Secret Key Cryptography and Public Key Cryptography?

Public key cryptography (Asymmetric key encryption) is a method that uses two separate keys for encryption and decryption while secret key cryptography (symmetric key encryption) uses a single key for encryption and decryption. Public key encryption is used for short messages while secret key cryptography can be used for longer messages.

3. What are the objectives of cryptography?

Cryptography is a method of using data security to prevent illegal access. It is employed in the blockchain to safeguard transactions between two nodes in a blockchain network. It focuses on the security of your transactions, and precautions against double-spending. It aids in safeguarding various blockchain network transactions. Cryptography makes sure that only those people may acquire, read, and handle the transaction that is intended for them.

4. What is SAFER?

James Massey one of the creators of IDEA, was principally responsible for creating the SAFER (Secure and Faster Encryption Routine) family of block ciphers of Cyberlink Corporation. The early SAFER K and SAFER SK design both use encryption, but their round counts and key schedules are different.

5. What is the difference between Hashing and Encryption

The difference between Hashing and Encryption are as follows –

• Hashing is the method to transform information into a key or shorter fixed value that serves as a representation of the original data. Encryption is the technique of secure encoding data so that only an authorized user who is aware of the key or password can retrieve the original data, leaving everything else as useless information.
• Hashing is used to index and retrieve items from a database and it happens quickly. Encryption is used to change data to keep it hidden from others.

Also read: How to write a smart contract? | Step-by-Step Guide

p2p interview questions

P2P is an integral part of blockchain technology. With blockchain technology becoming popular and new job openings coming up daily, it is important to be familiar with different parts of blockchain technology to land your dream job. This section contains some key p2p interview questions and their answers that will help you ace your interview. 

1. What is a P2P Network architecture?

P2P Network or peer-to-peer network architecture computer network station where every workstation or node has the same capabilities and obligations. The P2P model is frequently compared with the traditional client/server architecture where some computers are dedicated to serving others. In a P2P network computer frequently acts as server and client and is responsible for sending and receiving data, with bandwidth and processing shared among all users.

Such a decentralized network is less prone to systemic failure and uses resources more effectively than traditional networks. P2P networks are utilized by Bluetooth-enabled devices and Internet-based communication services, although online file sharing has significantly fueled development. Each computer functions as both a server and a client in a peer-to-peer (P2P) network, sending and receiving data, with bandwidth and processing shared among all users.

Such a decentralized network is less prone to systemic failure and uses resources more effectively than a traditional network. Electronics powered by Bluetooth and Internet-based communication services utilize P2P networks.

2. How does a P2P network work?

A peer-to-peer network lacks a central authority, instead, every node (peer) is connected. There is no hierarchy and the network nodes are connected by a mesh network with a “flat” topology. Peer-to-peer networks are open, decentralized, and robust by nature. Since nodes provide and consume services simultaneously, reciprocity acts as the driving force behind participation.

Each node on the network works as a server and client to other computers or nodes on the network. The node in a decentralized system functions as a server, downloading files and sharing them with other nodes. The P2P network’s speed, security, and effectiveness are due to the ability of a node to simultaneously conduct sharing and receiving tasks. A P2P network works best when there are many active nodes in the blockchain network.

Ethereum interview questions

There is a huge demand for Ethereum developers in the market. Ethereum is one of the biggest blockchain platforms available right now. Many businesses are looking for Ethereum experts and it is the ideal time for a blockchain developer to find employment. We will go over the top Ethereum interview questions in this section.

1. What is the difference Between Bitcoin and Ethereum Blockchain?

Bitcoin is a decentralized digital currency that can be transferred on a peer-to-peer network. Ethereum is a software platform that runs on the Ethereum blockchain technology. Bitcoin was invented hoped to replace national currency while Ethereum hoped to leverage blockchain technology for maintaining a decentralized payment network and storing computer code. Ethereum smart contracts are more flexible than Bitcoin smart contracts. Smart contracts are written for Bitcoin and use Script and clarity while Smart contract use Solidity and Viper.

Also read: 10 Best web3 wallet | Price, Safety, Features

2. What is Enterprise Ethereum Alliance (EEA)?

To develop Ethereum as an enterprise-grade technology, the Enterprise Ethereum Alliance (or EEA), established in February 2017, brings together a variety of start-ups, Fortune 500 organizations, technology vendors, academia, and Ethereum subject matter experts. Though several tech firms and companies have been supporting Ethereum via Cloud services and promoting its adoption, most efforts towards its scalability, privacy, and interoperability remained dispersed until the Enterprise Ethereum Alliance was founded. EEA hopes to build, promote, and support the best practices in Ethereum technology, standard, and architecture and is capable of handling real-world applications.

3. What is Wei?

Wei is the smallest denomination of ether used on the Ethereum network. One ether = 1,000,000,000,000,000,000 Wei (1018) or one Wei is one quintillionth of an ether. Wei and other Ether denominations will help express tiny value transactions, particularly small ETH that is frequently used for transaction fees or when determining a transaction gas limit.

4. How are Ethereum tokens are created?

Ethereum tokens or also cryptographic tokens are fungible digital assets that are built on top of the blockchain. Numerous digital assets are stored on the blockchain; the block explorer and analytics website Etherscan.io alone includes over 900 prominent projects based on the popular ERC20 token standard. Ethereum tokens are created by deploying smart contracts. There are over 400,000 ERC20 token contracts but one native token – Ether (ETH). The Ethereum network produces ETH to compensate miners for their efforts in adding blocks to the blockchain. Since it is needed to pay the gas fees necessary for each transaction, it is essential to the platform.

5. What Is Truffle?

Truffle is a development environment, testing framework, and asset pipeline for the Ethereum blockchain. Some of the features of Truffle are –

• Built-in support to compile, deploy and link smart contracts.
• Automatic contract testing.
• Supports Console apps as well as Web apps
• Network Management and Package Management
• Truffle console to directly communicate with smart contracts
• Supports tight integration

Solidity interview questions

Since Solidity is used to develop smart contracts, a critical component of decentralized programs and applications that run on the blockchain system, it is also crucial that people have a thorough understanding of blockchain technology, how it operates, and other elements of the blockchain ecosystem. Aspiring Solidity developers need to know the responses to fundamental Solidity interview questions. This not only helps to make your preparation methodical and improves your chances of getting hired. 

Following that, here are some frequently asked questions about Solidity and Ethereum to assist you to get ready for the technical rounds of interviews with various firms.

Also read: Decentraland vs Sandbox: Complete analysis of the top Metaverses

1. What is Solidity?

Solidity is a comparatively new computer language that is growing rapidly. The Ethereum network team worked to create Solidity specifically for constructing and designing smart contracts. Solidity is an object-oriented language. We use it to create smart contracts to implement business logic and create transaction records for the blockchain system. It helps to create machine-level code that can be compiled on the Ethereum Virtual Machine (EVM). Solidity is similar to C and C++ and has concepts like variables, functions, classes, and arithmetic operations. Solidity is currently used extensively on Ethereum and other blockchains like Monax

2. How is Solidity different from other programming languages?

Most programming languages are interpreted just in time. Solidity is a high-level programming language that gets compiled and deployed on the blockchain that understands the Ethereum virtual machine. After you compile the code and it is deployed to run as a smart contract and anyone can interact with it. The programming language run either on your browser or computer while Solidity can run on any computer on the Ethereum blockchain. 

3. What is an enum?

Enums are methods for defining user-defined data types and are typically used to give names of integral constants to improve the maintenance and readability of the contract. Enums limit the variables to one of a few preselected values, these values of the enumerated list are called enums. Enums help to reduce the number of bugs in the code.

4. Name the tools that can be used for testing Solidity codes.

Since Solidity contracts are immutable we must check the security of the smart contract before they are deployed on the blockchain. We require time and knowledge to carry out the audit and this can be complicated. Several tools can be used for testing Solidity codes, the top ones are – 

• Slither 
• Security
• SmartCheck
• Oyente
• Mythril

5. A solidity file can contain how many smart contracts?

One Solidity file can contain several contracts, but all contracts within a file share a namespace. Using multiple smart contracts can provide more security to projects. You can create contracts within or nestled contracts to limit what a user can do and what they can call.

Hyperledger Fabric interview questions

Hyperledger Fabric is an open-source platform used to create blockchain applications. If you are applying for the position of blockchain developer you may be asked questions on Hyperledger Fabric. In this section we have focused on Hyperledger Fabric interview questions, you can increase your chances of getting employed by impressing the hiring manager with your responses to these questions.

Also see: Hire Hyperledger developers

What is Hyperledger Fabric?

The Linux Foundation launched the open-source, permissioned blockchain system known as Hyperledger Fabric in 2015. It is a general-purpose, modular framework that provides distinctive identity management and access control features. It is used for a range of business applications, including trade finance, loyalty and rewards programs, track-and-trace of supply chains, and clearing and settlement of financial assets.

How do transactions work in Hyperledger Fabric?

Businesses use Hyperledger Fabric to ensure quick and smooth transaction flow. Hyperledger Fabric performs the transactions using the execute-order-validate method. 

• When the client wants to start a transaction, they use the client application to send an application to the SDK. SDK changes the transaction request into a transaction proposal that is sealed with the specific cryptographic signature of the client. The transaction proposal is subsequently forwarded by SDK to peers who are in charge of endorsing it following the endorsement rules.
• The endorsed peers verify the transaction proposals. After verification, the peers start the chain code proposal specified in the proposal. 
• Before submitting the transaction, the target peer confirms that the proposal responses are identical.
• The target peers broadcast the transaction message to the ordering services. The transaction contains the Channel ID, read/write settings, and a signature from each endorsing peer.
• After the transactions are validated, they are added to the ledger in the shape of a block.

What is Kafka used for?

Kafka is used for real-time streaming data pipelines and applications. A streamlined application consumes streams of data, and a data pipeline consistently processes and transports data from one system to another. For instance, Kafka would be used to ingest and store streaming data while sending reads to the apps driving the data pipeline if you wanted to build a data pipeline that ingests user activity data to measure how people use your website in real time. Kafka is used as a massage broker solution that process and mediates communication between two applications.