The AS400 interview questions seek to know why AS400 is not software but hardware/server. It is an IBM introduced application system introduced in 1988. The architecture of AS400 is used in critical tasks and ERP applications of manufacturing and other industries where reliability is crucial. It is also popular with SAS users of the IBM database and users of Oracle’s database systems.

The AS400 server is bundled with DB2 and can also be run on Unix and other platforms, forming some interesting AS400 DB2 interview questions and answers. In an actual AS400, there are two parts, the DB2 and the OS400 hardware box. Hence the AS400 is a different concept when compared to the DB2. One is a server hardware box with an operating OS400 server, and the other is a database that runs in it.

The AS 400 execution of a command/ program needs to know where and which library to find. This part is the favourite for AS400 interview questions. To AS400, the library is an object collection, and whenever one logs in, the system loads the QSYS library. QSYS root library is the only library where the system defined library resides and contains all other created libraries that can be fetched using the # or Q appendix.

Thus one has IBM’s libraries like system library QUSRSYS, QHLPSYS and QSYS, the product library where the IBM product library is added automatically and removed after job completion, the current library or the library being worked on, and the user library which is user created and a non-IBM library. These are straightforward concepts for the AS400 admin interview questions.

The library commands also feature in the AS400 interview questions. To see the sizes and objects in any library, one uses the command DSPLIB. The source physical file is the file that has different object type’s sources.  It has a capacity of 32,768 members and is an example of an object in the source library. However, source members are not objects. When the member has complied, though, an object is created for that particular source member using the command CRTSRCPF. This could provide some insight into AS400 technical interview questions and AS400 administrator interview questions.

List of interview questions

Here is our list of 40- AS400 interview questions that could be easy AS400 interview questions, intermediate level AS400 interview questions based on the command chain and working of AS400 and advanced level of AS400 scenario based interview questions for those with some working experience of AS400 in an interview based on AS400 interview questions.

  1. What is the expansion of AS400?
  2. What is meant by ‘LPAR’?
  3. Explain the library and its types in AS400?
  4. Explain which library is loaded into the system when one logs in.
  5. Explain if QGPL is a system or user library?
  6. With what command can one see the sizes and objects in a library?
  7. Explain the source physical file, and how does one see all file members?
  8. What are the commands required to see a file’s record formats?
  9. Explain the process of changing a physical file’s record size?
  10. How are a file’s duplicate records arranged?
  11. How does one use the physical file to define a new field and refer to another file?
  12. When we do CHGPF, does a LEVEL CHECK ERROR occur? 
  13. Define what is a logical file and its types in AS400? 
  14. What is meant by DYNSLT?
  15. Explain differences in Dynamic select and access path.
  16. How is JDUPSEQ used in the AS400 server?
  17. What does JDFTVAL do in AS400?
  18. Explain differences between join logical files and non-join logical files?
  19. Explain the differences between a logical file and a physical file?
  20. Explain mapping options of the record format field in CPYF?
  21. What differences are there in COPYF and CRTDUPOBJ?
  22. What is meant by the AS400 access path?
  23. List the types of access paths, and how does one change a file’s access path?
  24. Explain the file default access path?
  25. What is the maximum field numbers present in a file?
  26. What is the RPG maximum number of parameters passed?
  27. What number of CL parameters can be the maximum number passed?
  28. What is the AS400 compile-time array? Explain with an example.
  29. What is an AS400 array, and how many types are there?
  30. What is meant by AS400 Pre run time array? Give an example.
  31. What is the AS400 data structure, and what are its uses?
  32. Explain with an example of the data structure?
  33. What is meant by the types of AS400 data structures?
  34. Explain PSDS- AS400 program status data structure with an example?
  35. Explain with an example the NFDS file information data structure of AS400?
  36. Explain how to create an AS400 subsystem?
  37. Explain with an example the compiler directive of AS400?
  38. Explain with an example of the AS400 data queue?
  39. Explain what is AS400 FTP and  FTP commands?
  40. What is meant by journaling commands?


Version 4.0 of the OS/400 has the Logical PARtitioning-LPAR, which empowers the running of multiple OS’s on the unit of the IBM System, making sure that the partitioning of systems allows one OS not to interfere with the memory or other system resources. Some of AS400, aka IBM iSeries are huge applications and home-grown standard ERPs needing a client-server mid-range architecture and a secure and robust system where little or no maintenance is required. It is also used to manage supply-chains, legal operations on databases etc., answering AS400 interview questions and answers. Also, expect the interviewer to ask RPGLE interview questions, AS400 RPG interview questions and AS400 testing interview questions.  All the best!

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