We hire smart people who get the job done. Yeah, we use a lot of Java. And RoR. And Hadoop, Cassandra, etc. We use AWS and we run a DC stuffed with custom-confi

We hire smart people who get the job done. Yeah, we use a lot of Java. And RoR. And Hadoop, Cassandra, etc. We use AWS and we run a DC stuffed with custom-configured servers. In general, the knowledge of a specific technology/language/framework we already use can be helpful, but not a requirement. Chances are, you don't know everything you need to know to do this job. So willingness and ability to learn is a requirement.