Blockchain Certification: Job Interview Questions You Need to Know

Blockchain certification - logoIf you’ve been following the most recent technological trends around the globe, you’ve more than likely heard about blockchain. More and more people are starting to look into blockchain certification - a way to unite your passion and love for blockchain with future career opportunities. As time goes on, an increasing amount of businesses worldwide are implementing the blockchain technology to develop various innovations. These companies require certified blockchain experts to help them work around the complex structure of the records list. To be able to score a job as such an expert, though, you will need to pass a job interview. That’s why today we’ll be looking at some of the most popular blockchain interview questions that you’ll need for both your job interview and to receive proper blockchain certification.

We’ll start with some basics, and later on, move on to the more advanced questions. If you have some blockchain training, this tutorial will be a great revision for you. If not, however - this is the perfect guide to start preparing for the interview!

Introductory Blockchain Questions

To start this guide off, we’ll look into some of the more introductory interview questions that you might receive towards the beginning of your job interview. These are mostly definition, comparison, and opinion-based questions. They are great for checking your general knowledge on blockchain and the related topics around it. After all, if you’re looking for that blockchain certification (and then a blockchain expert job afterward), you will need to be able to demonstrate both complex AND general knowledge on the topic.

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Question 1: Define ‘blockchain’.

You were probably expecting this, both you are going to need to be able to explain this in both your blockchain job interview AND to be able to acquire the blockchain certification.

Blockchain (and the technology around it) can become confusing fast. That’s why it’s very important that you show your ability to explain this difficult concept in a way that a person that has never heard of it would be able to understand.

Blockchain is a list of blocks of information. These blocks are tied together using a system known as cryptography.

Blockchain, as a thing, rose to mainstream fame thanks to cryptocurrencies, namely Bitcoin. That’s exactly what a lot of people relate it to - once you hear the term “blockchain”, one of the first things that would pop into your head would probably be cryptocurrencies and their structure. However, this does not mean that crypto coins are the only thing that blockchains are used for - not by a longshot! A lot of companies apply the technology behind the blocks to create new and interesting products that can then go on and become super successful, especially if they’re related to security and privacy.

Question 2: What is the main principle of blockchain?

If you’re working towards a blockchain certification, you are bound to hear this a lot. Experts, teachers and the community always makes sure to emphasize the importance of this principle, whenever there’s a debate about the applicability of blockchain going on.

The main principle of blockchain is that it is a method of transferring information between two parties that cannot be copied.

Question 3: Can you remove blocks from the main chain?

Yes. You can use specific filters to remove the blocks that you do not need. You don’t even need to worry about using some sort of third-party software to do so - block filtering is a default option within the chain itself.

Question 4: Concerning Bitcoin, explain how the transaction done via the cryptocurrency is encrypted.

During your blockchain certification process, you might encounter some trick questions. They’re even more popular during job interviews - and this is one of them.

The information about the transaction that you make isn’t at all encrypted. How does the data remain private, then? This is done with the help of the block hashing process.

Question 5: What is a ‘hash pointer’?

A hash pointer can be viewed as a string that is attached between the blocks of information within the blockchain. Hash pointers are what connect transaction data.

Question 6: What types of blockchain are there?

Probably one of the easiest blockchain-related questions that you might get during your blockchain certification or job interview - there are three types of blockchain: public, private and consortium (hybrid).

Question 7: What is a ‘node’?

Nodes are computers that are used to process the transactions that happen on the blockchain. These computers can be situated anywhere in the world, as long as they are connected to the network.

Question 8: What are the types of records stored within the blockchain?

There are two types of such records - block data and transaction data. All of this information can be easily accessed at any given time.

Question 9: What sort of a network is required for a blockchain?

To receive a blockchain certification, you are also required to know quite a bit about the systems and other areas surrounding it. Networks are also very important - after all, they are what blockchains are based upon.

A blockchain must be based on a peer-to-peer network. This is so because of a need to eliminate any possible third-party interference. Companies, for example, can use this to validate new blocks - this makes the process much easier and safer.

Question 10: How does a ‘peer-to-peer’ network work?

Blockchain developers implement what is known as “trusted nodes”. These are computers used as the initializers of the network. After that, every single new machine that connects to the network receives no information about it’s status up to that point.

These were the ten basic questions that you might get during your blockchain certification or job interview. Most of them don’t require proper blockchain training - they can be learned by simply browsing online.

Blockchain Certification - Advanced Questions

Now, let’s move on to some of the more advanced questions that are required to become a certified blockchain expert. These questions will simply require a bit more than what can be seen as common knowledge. The structure of the questions is likely to remain almost the same, yet you might be required to elaborate on your answers or think out of the box.

Blockchain certification - charts in computer

Question 1: How does the verification process for a block work?

Whenever a new block enters the blockchain, all of the nodes that are present within the chain need to verify it. Two very important points need to be verified - Proof-of-Work and if the transaction is legitimate.

During your job interview, you are more likely than not to get asked to explain what is Proof-of-Work. To put it very simply, it is a form of a blockchain consensus - if a person or a company wants to receive the token associated with that particular blockchain, they are going to have to enable their machines to mine the blocks. This mining process validates the before-mentioned transactions and is called a Proof-of-Work (PoW) consensus.

Question 2: Explain ‘encryption’.

Encryption is a process that the blockchain system performs to keep your data and private information secure. To an uninvited third party, encrypted files will appear as strings of completely randomly generated numbers. The only person or company that will be able to view the encrypted information will be the one to whom the information was addressed in the first place.

Question 3: What is a ‘trapdoor’?

Trapdoors are a way of implementing encryption into your data. A trapdoor can be easily calculated in one direction, but almost impossible to do so in the opposite. RSAs (algorithms holding public keys) are among the main users of trapdoors.

Question 4: What is ‘Metamask’?

This is one of the questions that you are likely to get asked if your blockchain certification has something to do with the Ethereum network (let’s say, you’re trying to become a certified blockchain expert in ERC-20-based networks).

Metamask is a web browser extension that allows you to interact and view Ethereum-based networks on your browser.

Question 5: Explain a ‘decentralized blockchain’.

First of all, you should mention that decentralization is probably the most important feature of the blockchain. It is what the system is built upon - decentralization means that no one person, company or anyone else owns the blockchain.

When the system was first invented, the whole premise of it was based around decentralization. The idea was that you could keep your private information private, and wouldn’t have to fear that anyone else was going to find and view it. A decentralized blockchain is one that does not belong to anyone and is instead kept functioning by a peer-to-peer network and its supporting nodes.

Question 6: What are the differences between ‘PoW’ and ‘PoS’?

PoW (or Proof-of-Work) utilizes a process which is known as mining to generate new blocks into the blockchain. The stronger the computing system that you have, the more efficient your mining processes will be. Once you mine a block of information (validate enough transactions), you receive your share of that blockchain’s tokens.

PoS (Proof-of-Stake), on the other hand, lets you stake your tokens for them to validate the transactions happening within the blockchain. The result is the same as with PoW (the more you stake - the more you receive), but PoS is much more cost-friendly since you don’t require any specific machinery or vast amounts of electricity to utilize it.

Question 7: Explain ‘forks’.

If you’re aiming to become a true certified blockchain expert and are super serious with your blockchain certification, this is a topic that you should study thoroughly.

Concerning blockchains, there are two types of forks that you can encounter - soft forks and hard ones. Both of them can only be implemented by the developers of the blockchain.

Soft forks are implemented to make some minor changes. It is usually unnoticeable, at least for the average user. Depending on the blockchain in question, soft forks can be quite a common occurrence.

Hard forks, however, are a whole different story. They are usually only implemented under extreme circumstances, and when there is no other choice. The forks change the whole system of the blockchain - needless to say, they are very controversial within the crypto communities.

To give you an example, Ethereum has once implemented a hard fork and is planning to do so shortly, too. The first hard fork was to recover from a breach of security (it divided the blockchain into two - Ethereum and Ethereum Classic). The second one (the one that should happen shortly) is going to transition Ethereum from a PoW-based network to a PoS one.

Question 8: What is ‘secret sharing’?

Secret sharing is an interesting security-related function that a blockchain possesses.

Once you share a file (information) with a few users of the blockchain via these functions, the information is split into parts. Only when all of the parts are combined, the file can then be viewed.

Bitcoin and Ethereum would be the most obvious answers. However, it probably won’t be enough to just name these two.

Some of the more popular platforms would include IOTA, EOS, and Hyperledger.

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Question 10: Name the main types of blockchain ledgers.

For the final advanced question to receive blockchain certification, I’ve chosen an easier one. The reason why it’s in the “advanced” category is that a significant amount of people tend to forget one of the types when asked this question during their interview or exam.

There are three types of blockchain ledgers - centralized, decentralized and distributed.


In this tutorial, we’ve looked over some basic and more advanced blockchain interview questions that you might receive either during your job interview or during an exam for the blockchain certification.

Remember to get a lot of blockchain training before you go and take the exam or go for the job interview. Practice a lot, study the materials, and you should be golden!

Blockchain certification - work desk

During the actual interview (or exam) try to elaborate on your answers as much as possible. This will show that you do indeed have a significant amount of knowledge on the topic and will increase your reputation with your potential employers or examiners.

Even though we’ve only covered 20 of the more popular blockchain certification questions, you should have a pretty good idea of what you can expect to be asked.

I wish you the best of luck with your blockchain interview questions and the path to becoming a certified blockchain expert!

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Recent User Reviews

Helpful I see

These questions on blockchain technology will help me in my future job interview, thanks a lot.

more on Etherium maybe

Personally I would like to see more questions that relate to ETH, like what are Etherium smart contracts. I think it is important to have broader knowledge in the interview.

I know more what to expect

Although interviews are unpredictable, this tutorial is helpful really

is bitcoin blokchain?

is bitcoin blokchain?

How blockchain differs?

I saw this question in another article and wonder how to answer it: How does blockchain differ from traditional databases??

what are identifiers?

can you tell me what are identifiers of blokchain?

Congrats! :)

Congrats! If you have already decided on a career in blockchain space, you have made the best decision in your professional life :)

Bitcoin bitcoin

I love bitcoin


Blockchain is undoubtedly a thriving technology.

which is better PoW or PoS?

which is better PoW or PoS?


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