One of the most frequently posed data engineer scenario based questions, be ready for this conceptual question. FIFO also known as First In First Out is the simple job scheduling algorithm in Hadoop which implies that the tasks or processes that come first will be served first. In Hadoop, FIFO is the default scheduler. All the tasks or processes are placed in a queue and they get their turn to get executed according to their order of submission. There is one major disadvantage of this type of scheduling which is that the higher priority tasks have to wait for their turn which can impact the process.