My resource managers are active and so is Job history server. All my worker nodes had been exiting randomly for some time but used to restart automatically. today, all my node managers are down. what could be the reason? My worker nodes are typical with Hdfs And yarn on them. hdfs is running fine. what does it indicate when all node managers are down? There was no unusual load on servers. also, if i restart them, it still goes down. please suggest what could cause this?