Nostr "Nodes" = Nostr Relays... how do you think this message gets to you?
Discussion
Through decentralized relays. Each of the relays that sent me your message has a different set of messages and they never try to sync up (well, it's not in the protocol). If all the relays synced with each other like Bitcoin nodes or the Facebook CDN, Nostr would not have a decentralized data layer, but a centralized and distributed one.