Welcome to the world as seen through the eyes of a cluster node! In order to ensure fault-tolerance and scalability, reactive applications have no choice but to embrace distribution. Unfortunately, this also means embracing the uncertainty and nondeterminism that comes with building networked applications: changes in link quality, network partitions and outages of individual nodes are scenarios that need to be addressed first-hand when designing such systems. In this talk you will learn about failure detectors, gossip protocols and split brain resolvers in the context of Akka Cluster. Required knowledge Attendees should have a basic understanding of networks (latency, bandwidth, temporary outages) as well as a basic knowledge of Scala in order to be able to follow code examples. Learning objectives sensibilize attendees to the trade-offs that need to be made when building clustered applications learn about the fundamental mechanisms on which Akka Cluster is built understand that a networked application is not just one application, but the cooperation between individual processes that need to probe for each other's availability and decide what to do when one or more of them are maybe unavailable all while not being able to talk with one another Manuel Bernhardt is a passionate engineer, author, speaker and consultant who has a keen interest in the science of building and operating networked applications that run smoothly despite their distributed nature. Since 2008, he has guided and trained enterprise teams on the transformation to distributed computing. In recent years he is focusing primarily on production systems that embrace the reactive application architecture, using Akka, Play Framework, Scala and Java to this end.