Rocket Internet Systems Engineer interview questions

It was very pleasent experience to apply for abroad company. First I've applied for the job through their career site. Then I've got an email from HR recruiter asking for a skype interview. The recruiter was very kind, she asked typical questions ( present yourself and why Rocket internet) also she explained to me the application process ( 3 rounds to assist: First with HR, second with the IT Lead, third with IT Lead and HR ), and beause I done myhome work I've passed to the second round. The second round was with IT Lead ( via Skype) , he was also very kind and was very professional and technical, he start to ask me technical questions from easy to hard like: - how any handshakes in TCP ? - difference between TCP and UDP ? - what is hard link and soltlink ? - script to me folders creation with ascending numbers in one line - some geek question: reveal what this command do ? ( lately after the call I've done some reseach and I found it was fork bomb ) The technical questions were easy, but because It was my first abroad exprience, I felt nervous which lead the IT lead to say to me " Stay optimistic .. !!!!" ... After coulpe days, I got that mail "Thank you for applying to Rocket internet ... " ... declining my application. Nevertheless, I wasn't successful in this application, I feel that I met very pleasent and professinel people.