1. What is difference between spring and spring boot? 2. Write code for singleton class in Java? 3. What is Marker interface? 4. What is concurrent hash map and how does it work? 5. How will you address performance issues in sql or oracle? 6. How is mapping done in hibernate ORM ? 7. How does spring boot application start and execute? 8. What is the difference between put method and post method? 9. How is authentication done in any Java application? 10. Write controller class and it’s structure in notepad ? 11. What is the scope of the spring bean , by default? 12. How does url look like and what are the different parts of a url? Mention application context path , request parameters and values if any 13.what are is the difference between Java and Java script? 14. How is application execution control flow from UI to middle layer or service layer ? 15. Mention a few design patterns and write its code in Java.