Top 30 Most Common as400 interview questions You Should Prepare For
Landing a job that leverages your AS400 skills requires more than just technical know-how. It demands confidence, clarity, and the ability to articulate your expertise effectively. Mastering commonly asked as400 interview questions is the key to unlocking your potential and acing your interview. By understanding the underlying concepts and practicing your responses, you can significantly increase your chances of success. This comprehensive guide will equip you with the knowledge you need to confidently tackle the most frequently asked as400 interview questions.
What are as400 interview questions?
as400 interview questions are inquiries posed by interviewers to assess a candidate's knowledge, experience, and skills related to the IBM AS400 (now IBM i) system. These questions cover a broad spectrum of topics, from fundamental AS400 concepts and data management techniques to programming languages like RPG and CL, system administration, security protocols, and backup and recovery strategies. The primary purpose of as400 interview questions is to determine whether a candidate possesses the necessary qualifications to perform effectively in a role that involves working with the AS400 platform.
Why do interviewers ask as400 interview questions?
Interviewers utilize as400 interview questions to gauge a candidate's overall competence and suitability for a specific role. They aim to evaluate not only technical knowledge but also problem-solving abilities, practical experience, and the ability to apply theoretical concepts to real-world scenarios. By asking a range of as400 interview questions, interviewers can assess a candidate's understanding of system architecture, data handling, security considerations, and their capacity to troubleshoot issues that may arise within an AS400 environment. The answers help them determine if the candidate can contribute effectively to the team and the organization.
Here's a quick preview of the 30 most common as400 interview questions we'll be covering:
1. What is AS400?
2. What does 'AS' in AS400 stand for?
3. What is LPAR?
4. How are devices managed in AS400?
5. What is a data area in AS400?
6. Explain commitment control in AS400.
7. What is a job in the context of AS400?
8. Describe how batch jobs are managed in AS400.
9. What is SQL/400?
10. What is journaling on the AS400?
11. What is a message queue?
12. What is a spool file?
13. What are user profiles?
14. How do you perform backup on AS400?
15. What is a library in AS400?
16. What is the default access path of a file?
17. What is the maximum number of fields in a physical file?
18. What is the maximum number of parameters passed in RPG?
19. What is the maximum number of parameters passed in CL?
20. What is a compile-time array in AS400?
21. Explain the CALL, CALLB, and CALLP formats.
22. Can you elaborate on database administration in AS400?
23. How do you optimize performance in AS400 systems?
24. What is the role of logical files in AS400?
25. Explain the use of subsystems in AS400.
26. Describe the purpose of a journal receiver.
27. How do you set up security for user profiles?
28. Explain the concept of group profiles.
29. Can you explain the significance of QTEMP library?
30. What are activation groups used for?
## 1. What is AS400?
Why you might get asked this:
This is a foundational question designed to assess your basic understanding of the AS400 system. Interviewers want to ensure you know what the system is and its purpose within an organization. Your answer sets the stage for further, more complex as400 interview questions.
How to answer:
Provide a concise definition of AS400 (now IBM i). Explain that it's a mid-range computer system designed for various business applications, including e-commerce, database management, and ERP. Briefly mention its reliability and integration capabilities.
Example answer:
"The AS400, now known as IBM i, is a mid-range server system built for business-critical applications. It's known for its robust architecture and integrated database, making it a reliable platform for things like e-commerce and supply chain management. I see it as a workhorse that handles essential operations efficiently."
## 2. What does 'AS' in AS400 stand for?
Why you might get asked this:
This question tests your attention to detail and knowledge of AS400's history. While seemingly simple, it demonstrates whether you have a fundamental understanding of the system's origins. It is also one of the common as400 interview questions.
How to answer:
Give the correct abbreviation and what it stands for: Application System.
Example answer:
"The 'AS' in AS400 stands for Application System. I remember reading about its evolution, and the name reflected its focus on business applications from the start."
## 3. What is LPAR?
Why you might get asked this:
Interviewers want to know if you're familiar with virtualization concepts within the AS400 environment. This question assesses your knowledge of system resource management and the ability to isolate workloads. This is one of the more technical as400 interview questions.
How to answer:
Explain that LPAR stands for Logical Partitioning. Describe how it allows multiple operating systems or instances to run concurrently on a single physical machine, isolating resources for each partition.
Example answer:
"LPAR stands for Logical Partitioning. Essentially, it's a way to divide a single AS400 server into multiple virtual servers. This allows each partition to run its own operating system and applications independently. In a project, we used LPARs to isolate development, testing, and production environments on the same physical hardware, improving resource utilization."
## 4. How are devices managed in AS400?
Why you might get asked this:
This question evaluates your understanding of how the AS400 system interacts with peripheral devices. It checks if you know how to configure and manage hardware connected to the system. Answering this question correctly is important when answering as400 interview questions.
How to answer:
Explain that devices are managed through configuration descriptions. These descriptions define the properties and capabilities of connected devices such as terminals, printers, and disk drives. Mention the use of control language (CL) commands for managing device configurations.
Example answer:
"Devices in AS400 are managed through configuration descriptions. These descriptions define each device’s attributes, like its type and connection parameters. In one instance, I had to configure a new printer. We used CL commands to create a device description that matched the printer's specifications, ensuring it could communicate properly with the system."
## 5. What is a data area in AS400?
Why you might get asked this:
This question tests your knowledge of data sharing and storage mechanisms within the AS400 environment. Interviewers want to see if you understand how to share data between different applications or jobs. It can be included in as400 interview questions.
How to answer:
Explain that a data area is a small storage space used for sharing data across applications. Describe its use for storing global variables, system settings, or small amounts of shared data.
Example answer:
"A data area in AS400 is a small, named storage space used for sharing data between different programs or jobs. It's useful for storing global variables or configuration settings that need to be accessed by multiple applications. I once used a data area to store the current date for a batch processing system, ensuring all jobs used the same date for reporting."
## 6. Explain commitment control in AS400.
Why you might get asked this:
This question assesses your understanding of transaction management and data integrity within the AS400 environment. Interviewers want to know if you understand how to ensure that database transactions are processed reliably. It is one of the more conceptual as400 interview questions.
How to answer:
Explain that commitment control ensures transaction integrity. It involves completing all parts of a transaction successfully before committing changes to the database. If any part of the transaction fails, the entire transaction is rolled back.
Example answer:
"Commitment control in AS400 is a mechanism to ensure data integrity during database transactions. It allows you to group a series of database updates into a single logical unit. If any step in that unit fails, the entire transaction is rolled back, preventing data corruption. For example, during an order processing system, commitment control ensures that an order is only marked as complete if the inventory is successfully updated, and the customer is successfully charged."
## 7. What is a job in the context of AS400?
Why you might get asked this:
This question evaluates your basic understanding of how work is processed within the AS400 system. Interviewers want to ensure you know the fundamental unit of work in the AS400 environment. Its core knowledge when answering as400 interview questions.
How to answer:
Explain that a job is a unit of work handled by the system. It can be a batch job, an interactive job, or a subsystem job.
Example answer:
"In AS400, a 'job' refers to any unit of work that the system processes. This could be anything from running a batch program to an interactive session where a user is entering data. Think of it like this: Every task, big or small, is managed as a job by the AS400 system."
## 8. Describe how batch jobs are managed in AS400.
Why you might get asked this:
Interviewers want to know if you understand how to schedule and prioritize background processes within the AS400 environment. This tests your knowledge of workload management and system efficiency. It relates to more complex as400 interview questions.
How to answer:
Explain that batch jobs are managed through job queues. They can be scheduled and prioritized according to business rules and workload. Mention the use of job schedulers and CL commands for managing batch jobs.
Example answer:
"Batch jobs in AS400 are typically managed through job queues. These queues allow you to schedule and prioritize jobs according to business needs. For example, we used a job scheduler to run end-of-day reports automatically. Jobs are submitted to queues, where the system picks them up based on priority and available resources, ensuring the most important tasks run first."
## 9. What is SQL/400?
Why you might get asked this:
This question tests your familiarity with database management and querying techniques within the AS400 environment. Interviewers want to know if you can work with databases on the AS400 system. This is essential for solving as400 interview questions.
How to answer:
Explain that SQL/400 is a specialized version of SQL for managing databases on the AS400. It supports data manipulation, definition, and control commands.
Example answer:
"SQL/400 is IBM’s implementation of SQL for the AS400 environment. It allows us to interact with the DB2 database using standard SQL commands. I used SQL/400 extensively to write complex queries and stored procedures for data retrieval and manipulation. It’s a powerful tool for managing data on the system."
## 10. What is journaling on the AS400?
Why you might get asked this:
This question assesses your understanding of data recovery and auditing mechanisms within the AS400 environment. Interviewers want to know if you know how to protect data against loss or corruption. This is important when answering as400 interview questions.
How to answer:
Explain that journaling records changes to database files. It aids in recovery and auditing of data changes. Mention the use of journal receivers for storing journal entries.
Example answer:
"Journaling on the AS400 is a process of recording changes made to database files. It's crucial for data recovery because if something goes wrong, like a system crash, we can use the journal to roll back or reapply transactions to bring the database back to a consistent state. Also, journaling helps with auditing changes, showing who made what changes and when."
## 11. What is a message queue?
Why you might get asked this:
This question tests your knowledge of inter-process communication within the AS400 environment. Interviewers want to know if you understand how to facilitate communication between different applications or users. It can come up in as400 interview questions.
How to answer:
Explain that a message queue is used for storing messages between users or programs. It facilitates communication and synchronization.
Example answer:
"A message queue in AS400 is a way for different parts of the system – like programs or users – to send and receive messages. Imagine a system where one program generates a report and another program needs to process it. The first program can place the report's location in a message queue, and the second program can pick it up when it’s ready. This makes communication more reliable and flexible."
## 12. What is a spool file?
Why you might get asked this:
This question evaluates your understanding of print management within the AS400 environment. Interviewers want to know if you know how to handle output data streams for printing or online viewing. It is important for solving as400 interview questions.
How to answer:
Explain that a spool file holds output data streams until they can be printed or viewed online.
Example answer:
"A spool file holds data that’s intended for printing or viewing online. When a program generates output, it doesn’t immediately go to the printer. Instead, it’s stored in a spool file, which can then be managed separately. This lets you prioritize print jobs, reprint documents, and manage output more efficiently."
## 13. What are user profiles?
Why you might get asked this:
This question tests your knowledge of user management and security within the AS400 environment. Interviewers want to know if you understand how to define user identities, permissions, and environments. This is a basic concepts for as400 interview questions.
How to answer:
Explain that user profiles define user identities, permissions, and environments. Mention the use of commands like CRTUSRPRF, CHGUSRPRF, and DSPUSRPRF for managing user profiles.
Example answer:
"User profiles in AS400 are like accounts that define who a user is and what they can do on the system. Each profile includes a username, password, and a set of permissions that control access to different resources. Creating and managing these profiles is essential for security, ensuring that users can only access the parts of the system they need to."
## 14. How do you perform backup on AS400?
Why you might get asked this:
This question assesses your understanding of data protection and disaster recovery within the AS400 environment. Interviewers want to know if you know how to safeguard data against loss or corruption. This should be included in as400 interview questions.
How to answer:
Explain that backups are performed using commands such as SAVSYS, SAVLIB, SAVOBJ, and SAVDLO for system, library, object, and document library object backups, respectively.
Example answer:
"Backing up data on AS400 involves using various save commands, depending on what you need to back up. SAVSYS is used to back up the entire system, while SAVLIB backs up specific libraries. SAVOBJ is for backing up individual objects, and SAVDLO handles document library objects. I've used these commands to create full system backups and incremental backups, storing them on tape drives for offsite disaster recovery."
## 15. What is a library in AS400?
Why you might get asked this:
This question tests your understanding of how objects are organized and managed within the AS400 environment. Interviewers want to know if you understand the concept of libraries as containers for related objects. It is important to understanding as400 interview questions.
How to answer:
Explain that a library is a collection of related database files and programs. Common types include application libraries and system libraries.
Example answer:
"In AS400, a library is like a folder that holds related objects, such as programs, files, and other system components. It helps keep things organized. We typically have application libraries for specific software packages and system libraries for core system functions. Using libraries effectively makes it easier to manage and locate objects."
## 16. What is the default access path of a file?
Why you might get asked this:
This question tests your knowledge of how data is accessed and maintained within the AS400 database. Interviewers want to see if you understand the default behavior of file access paths. It can come up in as400 interview questions.
How to answer:
The default access path is immediate maintenance if not specified.
Example answer:
"The default access path of a file in AS400, if you don't specify otherwise, is immediate maintenance. This means that any changes to the data in the file are immediately reflected in the access path. This ensures that the access path is always up-to-date, but it can impact performance if there are frequent changes."
## 17. What is the maximum number of fields in a physical file?
Why you might get asked this:
This question tests your knowledge of file limitations within the AS400 database. Interviewers want to see if you understand the constraints of physical file design. This can come up in as400 interview questions.
How to answer:
The maximum number is 8000.
Example answer:
"The maximum number of fields you can have in a physical file on AS400 is 8000. This is a pretty high limit, but it's important to keep in mind when designing your database schema. If you need more than that, you might need to consider splitting your data into multiple files."
## 18. What is the maximum number of parameters passed in RPG?
Why you might get asked this:
This question tests your knowledge of RPG programming limitations within the AS400 environment. Interviewers want to see if you understand the constraints of parameter passing in RPG programs. Answering this question correctly is important when answering as400 interview questions.
How to answer:
The maximum is 255.
Example answer:
"In RPG, the maximum number of parameters you can pass to a procedure or subroutine is 255. It's a good practice to structure your code so that you don't exceed this limit, but if you do, you might need to rethink your design or use data structures to pass multiple values within a single parameter."
## 19. What is the maximum number of parameters passed in CL?
Why you might get asked this:
This question tests your knowledge of CL programming limitations within the AS400 environment. Interviewers want to see if you understand the constraints of parameter passing in CL programs. These limitations are important to understanding as400 interview questions.
How to answer:
The maximum is 40.
Example answer:
"The maximum number of parameters you can pass in a CL program is 40. When designing control language programs, you need to be aware of this limitation. Exceeding it would require restructuring your approach, perhaps by combining related parameters into a single data structure."
## 20. What is a compile-time array in AS400?
Why you might get asked this:
This question tests your understanding of data structures and programming concepts within the AS400 environment. Interviewers want to know if you understand how to use compile-time arrays for efficient data storage and retrieval. It is one of the more technical as400 interview questions.
How to answer:
Explain that a compile-time array is declared during program compilation. It is defined and accessed using fixed-size dimensions known at compile time.
Example answer:
"A compile-time array in AS400 is an array whose values are known when the program is compiled. You define the array and its initial values directly in the source code. This is useful for lookup tables or other data that doesn't change during program execution. For example, I used a compile-time array to store the names of the months, allowing the program to quickly convert month numbers to their corresponding names."
## 21. Explain the CALL, CALLB, and CALLP formats.
Why you might get asked this:
This question probes your understanding of program calling conventions in AS400, particularly in RPG. Interviewers assess your familiarity with different calling methods and their implications for performance and security. Be sure to include this when answering as400 interview questions.
How to answer:
Describe that these formats relate to calling programs in AS400. CALL is a standard call, CALLB is a bound call (more common and efficient), and CALLP is a procedure call, often used for security and control.
Example answer:
"In AS400, especially within RPG, CALL, CALLB, and CALLP are different ways to invoke other programs or procedures. CALL is the traditional method, while CALLB, or bound call, is generally more efficient. Then CALLP is the preferred method for calling procedures, and it provides better type checking and helps with modular programming practices."
## 22. Can you elaborate on database administration in AS400?
Why you might get asked this:
This question assesses your breadth of knowledge regarding database management on AS400. Interviewers are looking to understand your experience with database maintenance, performance tuning, security, and troubleshooting. Its core knowledge when answering as400 interview questions.
How to answer:
Explain that database administration involves managing and optimizing databases, including performance tuning, security, and data integrity.
Example answer:
"Database administration on AS400 is about ensuring the database is running smoothly and securely. This means regularly backing up data, monitoring performance, applying security patches, and optimizing queries. In a past role, I implemented a script to automatically reorganize physical files during off-peak hours, resulting in a noticeable performance improvement for end-users."
## 23. How do you optimize performance in AS400 systems?
Why you might get asked this:
This question explores your ability to identify and resolve performance bottlenecks in AS400 environments. Interviewers want to see if you can apply best practices for system tuning and resource management. It relates to more complex as400 interview questions.
How to answer:
Performance optimization involves tasks like disk tuning, system resource allocation, and query optimization.
Example answer:
"Optimizing performance on AS400 involves several key areas. First, disk tuning is crucial – ensuring data is efficiently stored and accessed. System resource allocation, such as memory and CPU, also needs to be monitored and adjusted as needed. I also focus on query optimization, rewriting inefficient SQL queries to reduce execution time. Regularly reviewing system logs and performance metrics is essential for proactive optimization."
## 24. What is the role of logical files in AS400?
Why you might get asked this:
This question assesses your knowledge of data access methods and indexing strategies in AS400. Interviewers want to understand how you use logical files to improve query performance. It is one of the more conceptual as400 interview questions.
How to answer:
Logical files are used to provide access paths to data, often for improved query performance by creating indexes.
Example answer:
"Logical files in AS400 provide different ways to access data in physical files. They're essentially indexes that allow you to retrieve data in a specific order or filter it based on certain criteria. We used logical files extensively to improve the performance of our reporting queries. By creating indexes on frequently used columns, we significantly reduced the time it took to generate reports."
## 25. Explain the use of subsystems in AS400.
Why you might get asked this:
This question tests your understanding of system resource management and job scheduling in AS400. Interviewers want to see if you know how to use subsystems to optimize system performance and workload distribution. Its core knowledge when answering as400 interview questions.
How to answer:
Subsystems manage groups of jobs to optimize system resources and provide job queues for efficient operation.
Example answer:
"Subsystems in AS400 are used to manage and control the execution of jobs. Each subsystem defines an environment in which jobs can run, including job queues, memory allocation, and priority settings. This allows you to isolate different types of workloads, such as batch processing and interactive sessions, ensuring that each receives the resources it needs without interfering with other workloads."
## 26. Describe the purpose of a journal receiver.
Why you might get asked this:
This question assesses your knowledge of data recovery and auditing mechanisms in AS400. Interviewers want to know if you understand how journal receivers are used to store journal entries for recovery and auditing purposes. It is important for solving as400 interview questions.
How to answer:
A journal receiver stores journal entries from various journals, aiding in auditing and recovery.
Example answer:
"A journal receiver in AS400 is used to store the actual journal entries that record changes made to database files. Journal receivers are important because they allow you to separate the journal entries from the journal itself, making it easier to manage and archive the entries. We use them extensively for auditing purposes, tracking who made what changes to the database and when."
## 27. How do you set up security for user profiles?
Why you might get asked this:
This question tests your understanding of user access control and security best practices in AS400. Interviewers want to see if you know how to configure user profiles with appropriate permissions and access levels. This should be included in as400 interview questions.
How to answer:
Security for user profiles involves defining permissions and access levels using commands like CRTUSRPRF and CHGUSRPRF.
Example answer:
"Setting up security for user profiles on AS400 involves carefully defining their permissions and access levels. We use commands like CRTUSRPRF to create new profiles and CHGUSRPRF to modify existing ones. We assign object authorities, which determine what users can do with specific objects like files and programs. We also use security officers to manage access to sensitive data and ensure that users only have the privileges they need to perform their jobs."
## 28. Explain the concept of group profiles.
Why you might get asked this:
This question assesses your knowledge of user management and security administration in AS400. Interviewers want to see if you understand how to use group profiles to simplify user administration and maintain consistent security policies. Answering this question correctly is important when answering as400 interview questions.
How to answer:
Group profiles manage permissions and access levels for multiple users, simplifying security administration.
Example answer:
"Group profiles in AS400 are used to manage permissions for multiple users at once. Instead of assigning permissions to each user individually, you can create a group profile and assign the necessary permissions to that group. Then, you add users to the group, and they automatically inherit those permissions. This simplifies security administration and ensures consistency across the organization."
## 29. Can you explain the significance of QTEMP library?
Why you might get asked this:
This question tests your knowledge of temporary storage and object management in AS400. Interviewers want to see if you understand the purpose and usage of the QTEMP library for temporary objects. It is one of the more technical as400 interview questions.
How to answer:
QTEMP is a temporary library used for storing temporary objects that are deleted when the job ends.
Example answer:
"The QTEMP library in AS400 is a temporary storage area unique to each job. Objects created in QTEMP are automatically deleted when the job ends. This is particularly useful for temporary files or work areas that are needed only for the duration of a specific program or process. Using QTEMP ensures that these temporary objects don't clutter the system and are automatically cleaned up."
## 30. What are activation groups used for?
Why you might get asked this:
This question assesses your understanding of memory management and resource isolation in AS400. Interviewers want to see if you know how activation groups are used to manage memory and resources for related jobs. Its core knowledge when answering as400 interview questions.
How to answer:
Activation groups manage memory and resources for related jobs, ensuring efficient use of system resources.
Example answer:
"Activation groups in AS400 are used to manage the lifecycle of resources and memory for related programs. They provide a way to isolate programs from each other, preventing one program from interfering with another. When a program is called, it runs within an activation group. When the activation group ends, all resources associated with it are released, ensuring efficient memory management and preventing resource leaks."
Other tips to prepare for a as400 interview questions
Preparing for as400 interview questions requires a multifaceted approach. Start by thoroughly reviewing the core concepts of the AS400 system, including its architecture, data management techniques, and programming languages. Practice answering common as400 interview questions out loud to improve your clarity and confidence. Conduct mock interviews with friends or colleagues to simulate the interview experience. Create a study plan that focuses on your areas of weakness. Make sure you are practicing with potential as400 interview questions. Use online resources, such as tutorials and documentation, to deepen your understanding of specific topics. Consider using AI-powered interview preparation tools to get personalized feedback and identify areas for improvement. By following these strategies, you can significantly enhance your preparedness and increase your chances of success.
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