To start with, what is a mainframe? This is is a computer used primarily by large organizations for critical applications like bulk data processing for tasks such as censuses, industry and consumer statistics, enterprise resource planning, and large-scale transaction processing.
Below are the top 25 questions and answers a mainframe is likely to face at the interview. Also, there are sample answers that should guide you on how you are supposed to answer the interview questions.
1. Why Are You Interested In This Role?
“After learning that there was an opening for this role in your company, I did not hesitate to make my application since I had all it takes to work with the mainframe. I would like to use the skills and knowledge that I have gained in the university and past experience to better the performance of your company. In addition, as you can see that I am still young and energetic, I still have the room to sharpen my skills and knowledge in this field by learning from you as well. Lastly, I would like to use my skills to earn a living and support my family too.”
2. What Are The Roles Of A Mainframe?
“The roles of a mainframe are;
· Mainframe is responsible for developing new system functionality, providing system maintenance & enhancements, and running and protecting the business by providing support for critical Risk applications.
- Adhere to security and control, Sarbanes-Oxley, and change control processes
- Design, develop and maintain Mainframe COBOL & JCL to meet support and/or project requirements.
- Interface with business and IT teams to understand business requirements and translate business requirements into formal technical requirements and application code.
- Work with IT support teams (EIA, DA/DBA, server teams) to ensure support and project requirements are developed and successfully implemented
- Develop and execute unit test and integration plans/scripts to validate that application changes meet technical specifications.
- Responsible for full System Development Life Cycle
- Work with business team to complete acceptance testing and participate in integration testing
- Participate in production support/pager duty rotation including weekend and off-hour support coverage
- Provide Solution Delivery Methodology artifacts associated with application components.
- Participate in technical reviews at appropriate stages of development
These are the duties and responsibilities that I would be delighted to perform in your company.”
3. Give Us Characteristics Of A Mainframe Computer
- They have bigger memory capacity.
- Have high processing power.
- It supports multiprocessing.
- Supports large number of users at the same time/ Supports several peripheral devices.
- Runs so many applications at the same time.”
4. What Are The Main Types Of Table Spaces That You Know?
“There are three types of tablespaces:
- Permanent – You use permanent tablespaces to store your user and application data. Oracle Database uses permanent tablespaces to store permanent data, such as system data. Each user is assigned a default permanent tablespace.
- Undo – A database running in automatic undo management mode transparently creates and manages undo data in the undo tablespace. Oracle Database uses undo data to roll back transactions, to provide read consistency, to help with database recovery, and to enable features such as Oracle Flashback Query. A database instance can have only one active undo tablespace.
- Temporary – Temporary tablespaces are used for storing temporary data, as would be created when SQL statements perform sort operations. An Oracle database gets a temporary tablespace when the database is created. You would create another temporary tablespace if you were creating a temporary tablespace group. Under typical circumstances, you do not have to create additional temporary tablespaces. If you have an extremely large database, then you might configure additional temporary tablespaces.”
5. What Are The Features Of A Mainframe Computer?
- They have good storage capacity. These systems have good storage capacity that makes the system process a huge amount of data as and when needed…
- Centralized server
- Throughput Computing
- Transactional Processing.”
6. What Are The Main Features Of COBOL?
- Allows you to handle a considerable volume of data due to its advanced file managing capability.
- Logical structure in COBOL is easier to read and modify.
- It can be executed and compiled on machines like IBM, personal computers, etc.
- Testing and debugging tools are always accessible on all platforms of the computer. Therefore, it is a robust programming language.
- You can easily debug in COBOL as it has different divisions.
- COBOL was designed for business-oriented applications. It can handle large volumes of data due to its advanced file handling capabilities.”
7. Name Various Types Of Divisions In COBOL Programme Structure
“Various divisions in COBOL program structure are as follows:
- Identification Division
- Environment Division
- Data Division
- Procedure Division.”
8. What Are COBOL Coding Rules?
“Here, some important syntax rules of COBOL:
- COBOL has syntax, which is very similar to the English language, that was designed to be self-documenting and very readable.
- Example: y = x; is represented with: MOVE x TO y
- It is not a case sensitive language.
- It has more than 300 reserved words
- Complex conditions can be “abbreviated” by removing repeated variables and conditions. For example:
- IS a GREATER THAN x AND y GREATER THAN OR EQUALS To
- It lacks big size standard library, as it has only 43 statements, 87 functions, and just one class.”
9. What Steps Do You Follow To Create A COBOL Program
“Steps to Create COBOL DB2 Program
- Step1: Create all these necessary tables.
- Step2: Create DCLGEN(optional)
- Step3: Precompile.
- Step4: Compile and Link Edit.
- Step5: DB2 BIND.
- Step6: Execute/Run the Program.”
10. What Is The Function Of An Update Cursor
The UpdateCursor function creates a cursor that allows you to update or delete rows on the specified feature class, shapefile, or table. The cursor places a lock on the data that will remain until either the script completes or the update cursor object is deleted..”
11. Why Do You Feel You Are Most Suited For This Role?
“Since a lot of mistakes can be done at the entry-level of mainframe development, your company can avoid this by choosing an experienced mainframe developer. I have gained a lot of skills and knowledge relevant to this industry. I would be delighted if you used my experience as an added advantage to me for the good of the company. Upon securing this position, I will not start from zero. I already know what it takes and what I am expected to do. This will also benefit this company in terms of saving cost and time to conduct training.”
12. Share With Us Your Greatest Achievement
“Since I started this job, I have received several awards out of my hard work. But to talk of the best awards, I have worked on various projects that are used in very busy environments. In 2018, I was awarded as the mainframe developer of the year. This came from a project we worked on for the county and came out successfully where we were awarded by the governor. I felt that this was one of the biggest achievements in my career. It is my hope that I will get a chance to perform and attain more goals and achievements in my career.”
13.Give Us Characteristics Of Mainframe Computers That You Know Of
· They have a bigger memory capacity.
· Have high processing power.
· It supports multiprocessing.
· Supports a large number of users at the same time/ Supports several peripheral devices.
· Runs so many applications at the same time.”
14. Talk About The Main Types Of Locks In Mainframe Computers
“There are three types of lock, namely:
· Shared – This type of lock permits two or more programs to read from the locked space but does not allow them to change it.
· Update – This lock is more lenient. It permits the program to read and change the locked space.
· Exclusive – This lock restricts all users from accessing the locked space.”
15. What Is The Difference Between SEARCH And SEARCH ALL In Computer Mainframe?
“The following are the key differences between SEARCH and SEARCH ALL
· SEARCH is a linear or sequential search while SEARCH ALL is a binary search.
· In SEARCH, initialization and incrementing of the index is required whereas in SEARCH ALL only initialization is required of an index. Incrementing is done automatically by the system.
· In SEARCH, multiple WHEN conditions can be coded, and while in SEARCH ALL only one WHEN condition can be coded
· In SEARCH, searching is slow and in SEARCH ALL search is very fast
· SEARCH can use on single-dimensional and multi-dimensional arrays while SEARCH ALL can use for only single dimensional arrays
· In SEARCH, data in the array need to be in sorted order while in SEARCH ALL data do not need to be in sorted order.”
16. What Are The Benefits Of Index 1 In the Mainframe?
· No more physical action after deleting or updating action until final commit
· Next-key locking is reduced to a minimum, dramatically improving concurrency
· Online index reorganization supported
· Can be created on columns whose length is greater than 255 bytes.”
17. Why Is Important To Have A Mainframe?
“Mainframe is very important in business since it helps in the following ways
· Helps in order processing of a customer
· Helps in preparing financial transactions
· Helps in production and inventory control
· Helps store bulk customer information and data
· Helps process payrolls.”
18. What Are The Different Types Of Table Spaces In The Mainframe?
· Permanent – You use permanent tablespaces to store your user and application data. Oracle Database uses permanent tablespaces to store permanent data, such as system data. Each user is assigned a default permanent tablespace.
· Undo – A database running in automatic undo management mode transparently creates and manages to undo data in the undo tablespace. Oracle Database uses undo data to roll back transactions, to provide read consistency, to help with database recovery, and to enable features such as Oracle Flashback Query. A database instance can have only one active undo tablespace.
· Temporary – Temporary tablespaces are used for storing temporary data, as would be created when SQL statements perform sort operations. An Oracle database gets a temporary tablespace when the database is created. You would create another temporary tablespace if you were creating a temporary tablespace group. Under typical circumstances, you do not have to create additional temporary tablespaces. If you have an extremely large database, then you might configure additional temporary tablespaces.
19. What Will You Offer To This Company In The Next One Month?
20. What Is Referential Integrity?
“Referential integrity refers to the relationship between tables. Because each table in a database must have a primary key, this primary key can appear in other tables because of its relationship to data within those tables. Referential integrity is the logical dependency of a foreign key on a primary key.”
21. What Is DRDA?
“DRDA stands for Distributed Relational Database Architecture. This is an architecture, developed by IBM, that enables relational data to be distributed among multiple platforms.”
22. What Is COPYBOOK In COBOL?
“A COBOL copybook is a type of flat file that describes the layout of records and fields in a COBOL data file.”
23. Where Do You See Yourself In The Next 5 Years
“First of all, in five years, I want to look at the work that I have done in this industry and feel that I have brought a change. My main focus is increasing sales for our clients by offering the best in the mainframe development field. All these activities that are involved in businesses require the mainframe department and I believe that I will work tirelessly to achieve more in this industry.”
24. What Kind Of Working Environment Would Be Best For You?
“I always prefer working in a busy environment. Being in a busy environment makes me observe a lot of things that may help me in my career. A busy environment will make me concentrate more on what I am doing and help others do the same as well.”
25. How Would People Around You Describe You?
“I believe that most of the people would refer to me as a creative, team player and a person who likes getting knowledge from the internet. I believe that most of the people who know me personally would describe me in that manner.”
Being a mainframe developer is a very exciting career that one can have. Answer the questions directly to the point and you will secure the position. All the best.