Amazon Devops Engineer interview questions

I received call from Amazon internal recruiter out of blue. I don't even remember when and what position I applied. I went to my job portal, seems that the jobs I applied I am not selected. But for a position they looked in their internal database and called me. Hiring manager called, He did say there are few others in the call. But haven't heard any one or no one asked any questions. Interview had lots n lots of technical questions on Linux, Linux administration, networking, database, web and hadoop. He did say he will ask 20 mins of general questions on linux/java. Next on hadoop. He seem to not know most of the answers for questions he asked. Because when I asked him more questions to understand correctly, he was not sure what to say. What is iNode on linux. and more details on that How do you check physical memory on Linux. How do you copy a local file to HDFS? What steps happen when a copy from local file to HDFS run? Explain the steps/channels When user accesses a url via a browser. What is distributed cache in hadoop? How do you measure network packet? If there are no cookies how do you make your application work? How did you make your application work with out cookies? How do you make your database work for high number of requests at peak hours? How do you make a background process run? How do you optimize database? How do you know how much memory your java application is taking on Linux? Tell me about garbage collection programming.