Skip to contentSkip to footer

Developer Mainframe Interview Questions

Salaries
Interviews

437 developer mainframe interview questions shared by candidates

Technical round: Basic JCL, COBOL, DB2, VSAM questions were asked. Scenario based File operations. SORT tricks. IDCAMS utility related questions. No need to read any book, if someone really worked in any project can answer the questions. Interviewer didn't prepare any questions, he talked with me and based on my response he was asking questions. There is a company CGI, I attended months back and before 2 days I attended the again (both telephonic). In both, the interviewer asked really same questions and in the same manner. Such a STUPID!! Managerial Round: Mostly Project related, Client related, my roles and responsibilities were asked. HR round: HR remembered me after 2 days of completion of managerial round. However, no communication since then.
avatar

Senior Mainframe Developer

Interviewed at DXC Technology

3.4★
Sep 21, 2019

Technical round: Basic JCL, COBOL, DB2, VSAM questions were asked. Scenario based File operations. SORT tricks. IDCAMS utility related questions. No need to read any book, if someone really worked in any project can answer the questions. Interviewer didn't prepare any questions, he talked with me and based on my response he was asking questions. There is a company CGI, I attended months back and before 2 days I attended the again (both telephonic). In both, the interviewer asked really same questions and in the same manner. Such a STUPID!! Managerial Round: Mostly Project related, Client related, my roles and responsibilities were asked. HR round: HR remembered me after 2 days of completion of managerial round. However, no communication since then.

1. However, the questions were not actually related to mainframe architecture. It were all related to the mainframe development experience. Question In a large bank if a program is accessing a file with millions of records how we can speed up the process Answer I told her about the cursors handling, call to procs handling to be managed better However she mentioned that it’s the indexing of the tables etc that needs to be done better. I Immediately got into a conflict with her and told her that indexing, views, etc would have already been created. She said yes, we need to do that more rigorously for all tables. I told her that for millions of records, we might be talking about 1000s of tables, she said yes, it worth investing the time. She told me that I needed to work on my development skills, which I agreed. Because the lady who was interviewing me had development experience and she had no idea about mainframe architecture. There was one male interview as well. I don't think he had any idea about mainframes, but he might be, you know, having mainframes little bit knowledge of mainframes, might have worked for a couple of years on mainframes. And I have worked on mainframes for 18 years. So that guy was asking me couple of questions which were not really on target. But its fine. Question Why to move to cloud Answer To optimize cost, speed to market, scalability etc. However some orgs may have reservations to move to cloud Question Why any org would not want to move to cloud Answer I don’t know, may be due some CID data etc or some regulatory requirements make them store the data on prem Question What regulatory requirements are you aware of which needs the data on prem Answer I don’t know, some of my customers were not ready to move all their data to cloud due to regulatory requirements. I can’t challenge them, when they say that it doesn’t need to be moved Question What are different approaches for mainframes modernization Answer At a high level 3 methods 1. Rehost 2. Rewrite 3. Re Architect Question He then gave an example and asked me what approach you will follow. Answer It was a clear case of Rehosting due to time, cost and scope/scale. Question What are the benefits of rehosting. Answer Speed, Cost and Scale. Question Tell me how cost will be reduced Answer I told the answer however , I slipped and said since we convert the code to Java the speed is also faster from programming language perspective. He said what? I said oops sorry, you caught me and corrected myself. THAT WAS THE END OF INTERVIEW AND I GOT THE MAIL THAT I WASN’T SELECTED. IT’S NOT ABOUT GETTING REJECTED SINCE I MYSELF REJECTED MANY OFFERS, SO IT’S FINE. THE FRUSTRATING THING IS THAT NON MAINFRAMES EXPERTS INTEVREIWNG MAINFRAMES EXPERTS OR AT LEAST DEVELOPERS INTERVIEWING ADMIN ETC MUST STOP.
avatar

Mainframes Modernization Consultant

Interviewed at Deutsche Bank

3.8★
Feb 19, 2026

1. However, the questions were not actually related to mainframe architecture. It were all related to the mainframe development experience. Question In a large bank if a program is accessing a file with millions of records how we can speed up the process Answer I told her about the cursors handling, call to procs handling to be managed better However she mentioned that it’s the indexing of the tables etc that needs to be done better. I Immediately got into a conflict with her and told her that indexing, views, etc would have already been created. She said yes, we need to do that more rigorously for all tables. I told her that for millions of records, we might be talking about 1000s of tables, she said yes, it worth investing the time. She told me that I needed to work on my development skills, which I agreed. Because the lady who was interviewing me had development experience and she had no idea about mainframe architecture. There was one male interview as well. I don't think he had any idea about mainframes, but he might be, you know, having mainframes little bit knowledge of mainframes, might have worked for a couple of years on mainframes. And I have worked on mainframes for 18 years. So that guy was asking me couple of questions which were not really on target. But its fine. Question Why to move to cloud Answer To optimize cost, speed to market, scalability etc. However some orgs may have reservations to move to cloud Question Why any org would not want to move to cloud Answer I don’t know, may be due some CID data etc or some regulatory requirements make them store the data on prem Question What regulatory requirements are you aware of which needs the data on prem Answer I don’t know, some of my customers were not ready to move all their data to cloud due to regulatory requirements. I can’t challenge them, when they say that it doesn’t need to be moved Question What are different approaches for mainframes modernization Answer At a high level 3 methods 1. Rehost 2. Rewrite 3. Re Architect Question He then gave an example and asked me what approach you will follow. Answer It was a clear case of Rehosting due to time, cost and scope/scale. Question What are the benefits of rehosting. Answer Speed, Cost and Scale. Question Tell me how cost will be reduced Answer I told the answer however , I slipped and said since we convert the code to Java the speed is also faster from programming language perspective. He said what? I said oops sorry, you caught me and corrected myself. THAT WAS THE END OF INTERVIEW AND I GOT THE MAIL THAT I WASN’T SELECTED. IT’S NOT ABOUT GETTING REJECTED SINCE I MYSELF REJECTED MANY OFFERS, SO IT’S FINE. THE FRUSTRATING THING IS THAT NON MAINFRAMES EXPERTS INTEVREIWNG MAINFRAMES EXPERTS OR AT LEAST DEVELOPERS INTERVIEWING ADMIN ETC MUST STOP.

Viewing 421 - 430 interview questions

Glassdoor has 437 interview questions and reports from Developer mainframe interviews. Prepare for your interview. Get hired. Love your job.