"Senior developers have years of experience in Java and have the knowledge and communication skills to mentor other developers. Companies prioritize strong technical skills and questions will focus on problem solving and critical thinking. A bachelor's degree in computer science or a related field, along with years of industry experience are standard."
How would you scale access to a system like Twitter
There's probably no real correct answer, though the solutions go from common to esoteric in a pretty normal progression: caching, shared-cache like memcache, optimize usage, prefetch, then get creative. This is more about testing reasoning and how far you'll go to solve a problem.
I was thinking geographically distributed servers.