What is a blockchain node?

A blockchain node is a critical component in a blockchain ecosystem. It is a computing device or server connected to the blockchain network, responsible for validating, verifying, and relaying transactions across the decentralized network. This role is crucial for maintaining the security, transparency, and reliability of the data shared in the blockchain. Nodes are not only responsible for validating transactions, but also for adding new information to the distributed ledger and propagating this information to other nodes in the network.

The fundamental role of nodes in the blockchain network

Nodes play a central role in maintaining the integrity of the blockchain, a decentralized and immutable ledger. The blockchain operates through the interaction of multiple nodes that perform specific tasks to validate and update blocks of data. A block is a set of validated transactions that are added to the chain. Each time a transaction is initiated on the blockchain, it must be validated by the nodes before being included in the ledger.

Blockchain nodes perform several essential functions:

• Transaction validation: Nodes verify each transaction to ensure it complies with network rules (e.g., the sender has sufficient funds, the digital signature is valid, etc.). This ensures that only valid transactions are accepted.
• Information propagation: When a node validates a block or transaction, it communicates it to other nodes in the network, thus enabling real-time updates of the blockchain on all nodes.

Nodes contribute to the decentralized blockchain ecosystem. This is because no central node controls the entire network. Each node is independent, but they all work together to ensure the network’s security and transparency.

Types of nodes in blockchains

There are different types of nodes depending on their role and the blockchain used. Here are the most common types:

Full knot

A full node is one that holds a complete copy of the entire blockchain—that is, all transactions since the first block (the Genesis block). This type of node plays a key role in validating new transactions and propagating blocks to other nodes. A full node independently verifies each transaction and block to ensure they comply with the rules of the blockchain protocol. It is directly involved in adding new blocks to the chain.

Lightweight Knot

A light node, or thin node, is a simplified version of a full node. Unlike a full node, it doesn’t download the entire blockchain, but only a portion of it. Light nodes perform less intensive work in terms of storage and processing. However, they rely on full nodes for up-to-date information. Light nodes are primarily used for mobile applications and light wallets, where users need to quickly verify transactions without downloading the entire blockchain history.

Validation Node

Validator nodes are those that have the ability to validate blocks and add them to the chain. This role is especially important in blockchains that use consensus mechanisms like Proof of Stake (PoS). These nodes are responsible for adding new blocks to the blockchain, based on the amount of cryptocurrency they own and “stake.” For example, in the Ethereum 2.0 network, validator nodes play a major role in updating the ledger without requiring the massive energy consumption of nodes using the Proof of Work (PoW) mechanism.

How a blockchain node works

Nodes are integrated into a blockchain network where each participant (node) must follow the same rules to properly interact with the rest of the network. To function optimally, nodes follow consensus mechanisms that ensure all parties in the network agree on the current state of the blockchain. Two main consensus mechanisms used are:

1. Proof of Work (PoW): This is the mechanism used by Bitcoin and other cryptocurrencies. In a PoW network, nodes, called miners, perform complex calculations to validate a block. This process is energy-intensive, but it is considered very secure.
2. Proof of Stake (PoS): PoS, used by blockchains like Ethereum 2.0, is more energy efficient. Nodes validate transactions based on the amount of cryptocurrency they hold and “stake.” The more cryptocurrency a node holds, the more likely it is to be selected to validate a block.

These mechanisms ensure that nodes can operate in a decentralized manner and consensus is achieved without the need for a trusted third party.

Advantages and Disadvantages of Blockchain Nodes

Like any system, blockchain nodes have advantages and disadvantages.

Advantages:

• Decentralization: A network of nodes allows the blockchain to operate in a decentralized manner, making it more resistant to attacks.
• Security: Nodes validate each transaction, reducing the risk of fraud or error.
• Transparency: All transactions are published on the blockchain, accessible to all nodes, thus ensuring complete transparency.

Disadvantages:

• Energy Consumption: Nodes using PoW, like those of Bitcoin, consume a significant amount of energy, which can be a hindrance for some users.
• Technical complexity: Setting up and maintaining a full node can be difficult for non-experts. Lightweight nodes are often preferred by those who don’t have the resources to manage full nodes.
• Hardware Requirements: Full nodes require significant hardware resources, particularly storage and computing power.

Blockchain nodes are essential to the proper functioning of decentralized networks. By validating transactions and enabling blockchain updates, they ensure the security and transparency of systems based on this technology. While their role is fundamental, it’s important to understand the different types of nodes and the consensus mechanisms that govern them. Whether you’re a user, developer, or investor, understanding blockchain nodes is crucial to understanding how blockchain works as a whole.

How do blockchain nodes work?

Blockchain nodes are the cornerstones of any decentralized network, ensuring the security and integrity of the blockchain. Their operation relies on a set of complex technical processes and consensus mechanisms to maintain an identical and updated copy of the blockchain across the entire network. To understand the role of nodes in more depth, it is essential to detail their interaction with transactions, how they validate these transactions, the consensus mechanisms they use, and how they interact with other nodes to keep the blockchain alive.

Transaction validation: a key process

Nodes are responsible for validating transactions submitted to the network. When a user initiates a transaction (e.g., sending cryptocurrency to another user), that transaction must first be verified to ensure its legitimacy before being added to the blockchain. Here’s how this process works:

1. Digital Signature Verification: Nodes verify that the transaction’s cryptographic signature is correct. Each transaction is signed by the user who initiated the request, thus guaranteeing its authenticity. If the signature is incorrect, the transaction will be immediately rejected by the node.
2. Balance and network rules verification: A node verifies whether the sender of the transaction actually has the necessary funds for the transaction. For example, in the case of Bitcoin, the node verifies that the originating address has the requested amount of Bitcoin. Additionally, each blockchain has specific rules that are built into the node software. This includes checks regarding previous blocks, timestamps, and other network parameters. If a rule is violated, the transaction will be rejected.
3. Validated transaction: If all checks are positive, the transaction is considered validated by the node and can be added to a block. Once a block is formed, it must still be validated by the network’s consensus mechanism.

Consensus mechanisms: an agreement between nodes

Blockchain nodes cannot simply accept or reject transactions arbitrarily. They follow a consensus mechanism, a method by which all nodes in the network agree on the validity of transactions and how the blockchain should evolve.

1. Proof of Work (PoW): Used by blockchains like Bitcoin, Proof of Work is a consensus mechanism that relies on complex mathematical calculations. Nodes called miners must solve complex equations before validating a block. This step requires significant computing power, making the blockchain secure but also energy-intensive. Each time a miner solves a problem, a block is validated and added to the chain. As a reward, the miner receives bitcoins.
2. Proof of Stake (PoS): Unlike PoW, Proof of Stake relies on a system where nodes are chosen to validate transactions based on the amount of cryptocurrency they have staked. The more cryptocurrency a node holds and stakes, the more likely it is to validate a block. This system is considered more energy-efficient than PoW and is used by networks like Ethereum 2.0. Nodes that correctly validate blocks are rewarded with cryptocurrency, while those that attempt to validate incorrectly risk losing part of their stake.
3. Proof of Authority (PoA): This mechanism is based on a trust model. Here, validator nodes are trusted entities that are authorized to validate transactions. This model is used by some private or semi-private blockchains and is often faster, but less decentralized.

Synchronization and Block Propagation

Once a block is validated by a node, it must be propagated to all other nodes in the network. Node synchronization is essential to maintain the integrity of the blockchain. When a node receives a validated block, it adds it to its local copy of the blockchain and transmits it to its neighbors.

Block propagation allows each node to ensure it has the most recent version of the blockchain. This rapid and continuous update allows all nodes to operate simultaneously without the need for a central node to control the network.

Attack resistance and network security

One of the major advantages of the decentralized blockchain model is its resistance to attacks. Indeed, to compromise a decentralized blockchain network, an attacker would need to control more than 50% of the nodes or computing power in the case of a PoW system. This makes attacks like double-spending extremely difficult to carry out.

1. 51% Attack: In a PoW blockchain, a 51% attack occurs when a malicious actor gains control of more than 50% of the network’s computing power. This would allow them to manipulate transactions, but such control is costly and difficult to achieve on largely decentralized networks.
2. Security through transparency: Every transaction validated on the blockchain is recorded immutably and transparently, accessible to all nodes. This transparency is one of the main safeguards against malicious manipulation, as all actions are visible and verifiable.

Nodes in Modern Blockchains: Recent Developments

Blockchain nodes are constantly evolving to adapt to the new demands of decentralized networks. For example, as part of the evolution to Ethereum 2.0, the transition from PoW to PoS was accompanied by numerous technical improvements regarding node management, their role, and efficiency.

• Scalability Improvements: Modern blockchains seek to improve the scalability of their networks to be able to process a higher number of transactions per second (TPS). Blockchain nodes must adapt to these developments to ensure efficient network management while maintaining its security and decentralization.
• Layer 2 Solutions: Technologies like Lightning Network for Bitcoin and Optimistic Rollups for Ethereum seek to reduce the load on nodes by moving some transactions off the main blockchain while maintaining security. These solutions can reduce the number of transactions each node must process, thus improving overall network performance.

Blockchain nodes play a vital role in the proper functioning of decentralized networks. They ensure transaction validation, blockchain integrity, and data security. The validation process relies on various consensus mechanisms, such as Proof of Work (PoW) and Proof of Stake (PoS), which ensure the network remains reliable and transparent. Additionally, nodes interact with each other to propagate information and keep the blockchain up to date, making the entire network resistant to attacks and manipulation. Finally, recent developments in blockchain technology show that nodes continue to evolve to improve network performance and scalability.

The Different Types of Blockchain Nodes

Blockchain nodes aren’t all the same. There are several types of nodes, each with specific functions and responsibilities in the blockchain ecosystem. Understanding the differences between these types of nodes helps us understand the role they play in maintaining the network, validating transactions, and improving blockchain performance. Let’s examine the three main types of nodes: full nodes, lightweight nodes, and validator nodes.

Full Nodes: The Foundation of the Network

A full node is a blockchain network participant that maintains a complete and up-to-date copy of the blockchain. These nodes play a key role in the security and decentralization of the network, as they store all blocks and transactions made since the blockchain’s creation. This type of node is essential for validating transactions and recording blocks.

Role of Full Nodes

• Transaction Validation and Propagation: A full node is responsible for validating the transactions sent to it. When light nodes or other participants send transactions to the network, full nodes ensure they comply with protocol rules, such as verifying digital signatures, fund availability, and the absence of double spending.
• Blockchain storage and updating: A full node maintains an entire copy of the blockchain. It constantly updates its database to incorporate newly validated blocks. In other words, each full node has the complete transaction history, allowing it to verify the integrity of the network and resist any attempts at manipulation.
• Network security: By maintaining a complete local copy of the blockchain, these nodes actively contribute to the security of the entire network. They make the network less vulnerable to attacks because data is distributed and synchronized across many nodes, making manipulation extremely difficult.

Disadvantages of Full Nodes

While full nodes are essential to the decentralization and security of a blockchain network, they do have some drawbacks:

• Resource Consumption: Full nodes require significant storage because they must maintain the entire blockchain. This can amount to several hundred gigabytes of data, which can be a hindrance for users with limited hardware resources.
• Bandwidth Requirements: Since these nodes must constantly synchronize and propagate information to other nodes, they require stable and fast internet bandwidth to operate efficiently.
  

Lightweight nodes: more accessible solutions

Lightweight nodes, also known as “SPV” (Simplified Payment Verification) nodes, are an alternative to full nodes. These nodes do not maintain a complete copy of the blockchain, but only the information essential to verify transactions.

Role of lightweight nodes

• Fast transaction validation: Light nodes rely on full nodes to verify transactions. Instead of downloading the entire blockchain, they download only the block headers. This allows them to verify that transactions are part of a validated block without needing a full copy of the blockchain.
• Use in mobile wallets: Lightweight nodes are particularly used in cryptocurrency wallet applications on mobile devices because they consume little data and resources. They allow a user to send and receive cryptocurrencies without having to manage a full node.

Advantages of Lightweight Knots

• Low resource consumption: Unlike full nodes, lightweight nodes require little storage space and bandwidth, making them well-suited for users who want to interact with the blockchain without investing in powerful hardware.
• Accessibility: Lightweight nodes allow a greater number of users to participate in the blockchain ecosystem because they are much easier to set up and maintain.
  

Lightweight Node Limits

However, lightweight nodes have limitations:

• Less security: Because lightweight nodes rely on full nodes to validate transactions, they are vulnerable to attacks, such as those involving incorrect information transmitted by malicious nodes. In other words, a lightweight node is less reliable in ensuring network integrity.
• Full Node Dependence: Lightweight nodes rely entirely on full nodes to verify transactions. If full nodes become obsolete or are compromised, lightweight nodes can no longer operate reliably.

Validation Nodes: A Specialized Approach

Validator nodes are often used in Proof of Stake (PoS) systems, such as Ethereum 2.0. These nodes play a specific role in the block validation process based on the amount of cryptocurrency they hold at stake. Unlike full and light nodes, these nodes are not tasked with verifying each transaction individually, but rather with adding new blocks to the blockchain using the PoS consensus mechanism.

Role of Validation Nodes

• Block Participation: These nodes are responsible for creating new blocks, which they validate based on the cryptocurrency they have staked. When a node is selected to validate a block, it verifies the transactions and proposes the block to be added to the chain.
• Validation Rewards: Since validator nodes are essential to the security of the PoS blockchain, they receive cryptocurrency rewards when they successfully validate a block. This encourages participation and network security.

Benefits of Validator Nodes

• Energy efficiency: Validator nodes, used in systems like PoS, are much more energy-efficient than PoW validator nodes. They do not require high computing power, making the blockchain more sustainable and accessible.
• Network security: Validator nodes ensure the security of the blockchain by actively participating in the addition of new blocks. The staking system ensures that nodes act honestly, as they risk losing part of their stake if they act maliciously.

Blockchain nodes—whether full, lightweight, or validator—all play a fundamental role in the proper functioning of decentralized networks. Full nodes are essential for the security and decentralization of the blockchain, while lightweight nodes offer a more accessible solution for users wishing to interact with the blockchain without maintaining a full copy. Validator nodes, on the other hand, ensure the addition of new blocks in Proof of Stake-based systems. These different types of nodes ensure the diversity and robustness of modern blockchains, making these networks flexible, accessible, and secure.