A seed node is a special node that allows the incorporation of new nodes to the network and maintains the strength of the network at all times, by allowing them to synchronize and obtain a copy of the data from the blockchain, replicating it and adding resistance and security to it.

UThe seed node is one of the most important parts within the formation of the Bitcoin network. These nodes have the responsibility to be "Trackers" in the Bitcoin system to locate other nodes, and assist in the process of connecting to other nodes that are becoming part of the network.

It is through these seed nodes that it is possible to locate other nodes that are connecting to the network and that are running a Bitcoin client. That is to say, These nodes create a list of pairs with the IP addresses of the other nodes that operate within the network and serve as a bridge to link the new nodes to the rest of the network..

However, even though they are called a seed node, they do not necessarily have to be complete nodes. Since they do not need to run a full Bitcoin client as such to function. Instead, to perform the function of trackers, these nodes must be connected to the Bitcoin network constantly and uninterrupted.

How does a seed node work in Bitcoin?

Bitcoin has a series of seed nodes that are used to locate active nodes. From these nodes, another new node that wants to enter the network, can connect. That is, the seed nodes are used only to locate or find complete nodes that are running the Bitcoin client. Sort of like an address book that tells other nodes who to go to in order to be part of the network. Surprising isn't it? This means that Bitcoin organizes its network in such a way that even new nodes find it easy to start being part of the Bitcoin network.

Thus when a new node wants to join the Bitcoin network, it must briefly connect to a seed node. This will indicate or provide you with a list of the IP addresses of the nodes that are active within the Bitcoin network, and through which you can connect to the system. Thus, the seed nodes execute their function within the Bitcoin system as IP address locators. Therefore, they cannot be used for block mining or for the reception and validation of transactions. Rather, they are used only so that the new nodes can enter and connect to the peer network through the active nodes.

Then, Bitcoin's seed nodes serve as a link medium through which new Bitcoin nodes and clients can connect to the network. Once the list of nodes is delivered, the new nodes connect to these nodes and begin the process of synchronization with the network.

Functions of seed nodes in Bitcoin

Bitcoin, to be a decentralized system, employs a peer network known as Peer-to-Peer (P2P) that maintains communication as equals within the network. In this system, the nodes are interconnected with each other to carry out the transfer and exchange of information quickly, safely and easily. And for this they use the same consensus rules for everyone.

So, when a new node wants to gain access to the network, it must connect with a seed node, which is a Bitcoin client that is always active and has a static IP address. This client operates as a gateway to the Bitcoin network, being one of the first connections that Bitcoin clients make at the beginning.

Thus, seed nodes play an important role within the network, operating from highly trusted servers. Allowing new clients to connect to the network automatically and without the need for manual intervention by a user. Although it may be the case that some of these nodes can become dishonest, causing a negative impact within the network. So it is not recommended to place trust in a single seed node.

DNS seed servers

In Bitcoin when the nodes connect for the first time, they do not know the IP addresses of any of the full nodes that are active on the network. So they require connecting to a seed node to obtain these IP addresses. Only then can they connect to at least one of the active complete nodes regardless of where it is geographically located.

So, when finding the peers with which a new incoming connection can be established for the new nodes, the seed nodes have two options: they query the Bitcoin seed DNS or directly connect to the encoded seed nodes within Bitcoin.

Seed DNS seeks to facilitate the task of obtaining and providing the list with the IP addresses of the complete nodes to the new nodes that wish to join the network for the first time. So these servers are one of the mechanisms that the Bitcoin network uses to provide, in a reliable and secure way, a list with the IP addresses of the complete stable nodes that remain connected to the system and with which a new connection can be established. .

After a new connection is established with any of Bitcoin's active full nodes, the new node sends a message with its IP address to the nearest or closest node it has. Who in turn will forward the message with the IP address of that new node connected to the closest node. This process is carried out by the active nodes in succession in order to publicize the new node connected in the network. And so a good connection can be established with this new node.

On the other hand, in the Bitcoin network two types of DNS seed servers are managed: dynamic DNS servers and static DNS servers. In the first case, IP addresses are obtained automatically every time a scan is made to the network; so these servers provide a list of full active nodes on the network. Whereas static DNS servers use manual updates to obtain the IP addresses of the complete nodes. Making it more likely to add IP addresses of nodes that are no longer active on the network.

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Are seed nodes essential for network security and network performance?


Thanks to the seed nodes, blockchain networks are able to receive new nodes and help them in their synchronization process. This is a process that helps strengthen their security, resistance to censorship and resilience, making them an essential part of their operating structure.

Seed node in other blockchains

While Bitcoin has been the first to implement seed nodes, this functionality is not unique to Bitcoin. The rest of the cryptocurrencies that follow the network scheme implemented by Bitcoin also use this system to allow the operation of their network. For example, in Ethereum we can see the bootnodes, which are nothing more than the seed nodes of the network. These nodes are accessible via DNS or through the nodes already encoded in your clients, as we can see in this link.