CompactNode
A single entry in a DHT compact nodes / nodes6 list: a 20-byte NodeId followed by a compact DhtEndpoint. This is the on-wire form produced by libtorrent's write_nodes_entry (src/kademlia/node.cpp), which concatenates id and write_endpoint(ep) for each node.
A v4 entry is therefore 26 bytes (20 + 6); a v6 entry is 38 bytes (20 + 18).