All validators on Avalanche must validate on the “default subnet”. This subnet consists of three chains: Platform Chain – This chain stores the network metadata (i.e., what subnets and blockchains exist, who is validating what, etc.). Exchange Chain – This chain supports asset creation and trading. Contract Chain – This chain is an Ethereum Virtual Machine instance that runs on Avalanche’s Avalanche consensus. Asides this requirement, validators are free to choose which subnets they want to validate on, and they do not have to run multiple nodes to validate on multiple subnets, unless it is a requirement by the subnet.