Hey @mayukha. When a transaction is is supposed to be written on the Blockchain, the majority of the nodes in the network must validate it and verify it to be authentic, only then the transaction is added on the Blockchain. Practically, most of the nodes verify only authentic transactions and if any node is trying to approve a fake transaction, it'll not be accepted. But there's a chance that if the majority of the network approves a fake transaction, then an unauthentic transaction will be written on the Blockchain.