How does a bitcoin node select its "current" chain [duplicate]
How does a bitcoin node select its "current" chain [duplicate] This question already has an answer here: Strongest vs Longest chain and orphaned blocks 1 answer Suppose a bitcoin client can build many different (maximal) chains from the blocks it has received so far. Which is it going to choose as its current chain? That decision cannot be made on the basis of which chain is the longest. Else, a malicious party could build a chain -longer than the current main chain- at ultra-low difficulty (hence very fast and cheap to build). This fake chain 1) would be perfectly valid, and 2) would convince every node that it is the "current" chain. http://ift.tt/2hwF72m