Peer Discovery

Peer discovery is how a blockchain node finds other nodes to connect to when it starts up and as its connections change over time. A fresh client knows nothing about the live network, so it contacts a small set of known entry points — hardcoded bootstrap nodes, DNS seeds, or a distributed lookup table such as Ethereum's discv5 — collects the addresses of active peers, and then keeps refreshing that list on its own. Good peer discovery matters for both decentralisation and safety: a node with a diverse, well-spread set of peers is much harder to isolate in an eclipse attack, where an attacker surrounds a node with machines it controls in order to feed it a false view of the chain.