"Junior developers are often responsible for writing the more monotonous and simple code required by senior members of the development team. Because of this, interviews will be designed to test your knowledge of the fundamentals of Java so be prepared to answer technical questions that you likely came across in college. Data structures and algorithms will be heavily emphasised. A bachelor's degree or equivalent work experience is required. "
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.