Dear agraeb, this highly depends on the individual Blockchain network. The rules of the respective ledger determine who can become a consensus relevant node. Public proof-of-work blockchains, such as Bitcoin and Ethereum (for now) can be joined by anyone with the appropriate hardware to become a node. Both ecosystems offer a variety of network clients - usually open source - to run the node in line with the consensus protocol of the respective peer-to-peer network. For details on a specific Blockchain network or network client, we recommend consulting their respective documentation. I hope this helps - KS
Who host the blockchain network that are floating on the internet? How one knows to communicate correctly with another node?
Dear agraeb, this highly depends on the individual Blockchain network. The rules of the respective ledger determine who can become a consensus relevant node. Public proof-of-work blockchains, such as Bitcoin and Ethereum (for now) can be joined by anyone with the appropriate hardware to become a node. Both ecosystems offer a variety of network clients - usually open source - to run the node in line with the consensus protocol of the respective peer-to-peer network. For details on a specific Blockchain network or network client, we recommend consulting their respective documentation.
I hope this helps - KS