Worst interview process in the entire world.
I did a ton of prep for this interview particularly around arch design. All the resources online are fairly generic and similar (how would you design twitter, facebook photos etc.). These will not help you at all. I had work experience that helped me with design but they ended up drilling down into how exactly I would shard and distribute traffic across the DB nodes and at that point I didn't know what to say as this is not a common application programmer's task. What I cooked up (I have basic knowledge of Map Reduce/Elastic Search architecture) was insufficient.
Things like this - knowledge based questions with extreme specificity.
Also recruiter was THE WORST recruiter, it took several months to schedule the interview because she would repeatedly not respond to me. I had an internal referral so every time I would email her, after 3 false attempts over at least a 2 week period, I'd ping my reference to prompt her to respond.