Contents
Key Takeaways
COBOL still powers 220+ billion lines of code, running critical banking, insurance, and government systems.
70% of business transactions globally rely on COBOL, making it one of the most used yet underrated languages.
COBOL developers are scarce—retirements create a talent gap, but demand for modernization and maintenance is huge.
Core interview focus: batch vs online processing, file handling, JCL integration, debugging mainframe jobs, and system optimization.
Red flags: weak understanding of legacy-to-modern system integration, lack of attention to detail, or inability to debug production jobs.
Future relevance: modernization projects mean COBOL pros who also know Java, Python, or cloud are especially valuable.
Why COBOL Skills Matter Today
COBOL has been running critical business systems for 65 years, with an estimated 70-80% of the world's business transactions still processed in COBOL.
But most internet websites doesn’t give the key COBOL interview questions that matter, so we thought to research and write it down for you.
Despite being created in 1959, over 24,962 companies worldwide actively use COBOL, with market presence in insurance (531 companies), software development (480 companies), and wealth management (470 companies).
The skills shortage is real. More than 60% of organizations using COBOL report that finding skilled developers is their biggest challenge.
For engineering leaders at companies under 200 employees, this creates both a risk and opportunity. While estimates suggest between 220-800 billion lines of COBOL code remain in active use globally, the talent pool continues shrinking as experienced developers retire.
As an engineering leader who has analyzed hiring patterns across the industry, I've observed that companies maintaining legacy COBOL systems often face project delays and increased costs due to talent scarcity.
This guide provides the framework to identify and assess COBOL talent effectively.
What is COBOL and Key Skills Needed
COBOL (Common Business-Oriented Language) is a compiled, English-like programming language designed specifically for business operations. Created by a consortium led by Grace Hopper, Mary K. Hawes, and Jean Sammet, it prioritizes readability and data processing efficiency.
Core COBOL Skills Required:
Understanding of four division structure (Identification, Environment, Data, Procedure)
File handling expertise (sequential, indexed, relative)
Data manipulation and validation techniques
Integration with modern systems and databases
Legacy system maintenance and modernization
Modern Integration Skills:
API development and web services exposure
Database connectivity (DB2, Oracle, SQL Server)
Cloud platform deployment
DevOps and version control practices
The key differentiator for strong COBOL developers is their ability to bridge legacy systems with modern architectures while maintaining system stability.
Did you know?
COBOL was created in 1959, making it older than the internet itself.
Still think COBOL is outdated?
Over 70% of the world’s transactions rely on it. With Utkrusht, you can hire COBOL experts who keep legacy systems running and modernize them for the future. Get started today and secure your talent pipeline.
20 Basic COBOL Interview Questions with Answers
1. What is COBOL and what are its primary uses?
COBOL stands for Common Business-Oriented Language. It's a high-level programming language designed for business, financial, and administrative systems. COBOL excels at processing large volumes of structured data and handling business logic.
What an ideal candidate should discuss: The candidate should mention COBOL's English-like syntax, its strength in batch processing, and its continued use in mission-critical systems across banking, government, and insurance sectors.
2. Explain the four divisions of a COBOL program.
The four divisions are:
IDENTIFICATION DIVISION: Contains program metadata (name, author, date)
ENVIRONMENT DIVISION: Defines system-specific configurations and file assignments
DATA DIVISION: Declares variables, file structures, and data definitions
PROCEDURE DIVISION: Contains executable program logic and business rules
What an ideal candidate should discuss: They should emphasize how this structure improves code organization and maintainability, making COBOL programs self-documenting.
3. What is the difference between WORKING-STORAGE SECTION and LOCAL-STORAGE SECTION?
WORKING-STORAGE variables retain their values throughout program execution and between calls. LOCAL-STORAGE variables are reinitialized each time the program is called and don't persist between executions.
What an ideal candidate should discuss: The performance and memory implications of each section, particularly in programs that are called frequently.
4. Explain the purpose of the PICTURE clause.
The PICTURE clause defines the data type, length, and format of a variable. It specifies how data is stored internally and how it should be displayed.
What an ideal candidate should discuss: Different picture character meanings (9 for numeric, X for alphanumeric, V for decimal point) and editing symbols for formatted output.
5. What is the difference between PERFORM and CALL statements?
PERFORM executes internal procedures (paragraphs or sections) within the same program. CALL invokes external programs or subprograms, creating a new execution context.
What an ideal candidate should discuss: Performance implications, parameter passing differences, and when to use each approach for modular programming.
6. How do you define and use tables in COBOL?
Tables are defined using the OCCURS clause and accessed using subscripts or indexes.
What an ideal candidate should discuss: The difference between subscripts and indexes, and performance considerations when working with large tables.
7. What are the different file organization methods in COBOL?
Sequential: Records processed in order (tape-like access)
Indexed: Direct access via key fields (ISAM/VSAM)
Relative: Direct access by record number
What an ideal candidate should discuss: When to use each organization type based on access patterns and performance requirements.
8. Explain the concept of REDEFINES in COBOL.
REDEFINES allows the same storage area to be interpreted as different data structures, enabling union-like functionality.
What an ideal candidate should discuss: Memory efficiency benefits and caution needed when using REDEFINES to avoid data corruption.
9. What is the significance of the COMP clause?
COMP (computational) clauses define how numeric data is stored internally for optimal processing efficiency.
COMP (COMP-4): Binary format
COMP-3: Packed decimal format
DISPLAY: Standard readable format
What an ideal candidate should discuss: Storage efficiency and performance trade-offs between different computational formats.
10. How do you handle conditional processing in COBOL?
COBOL uses IF-THEN-ELSE and EVALUATE statements for conditional logic.
What an ideal candidate should discuss: The importance of proper END-IF usage and when to use EVALUATE for multiple conditions.
11. What are level numbers and their significance?
Level numbers (01-49, 77, 88) define data hierarchy and relationships in the DATA DIVISION.
01: Record level
05-49: Elementary or group items
77: Independent items
88: Condition names
What an ideal candidate should discuss: How proper level numbering creates clear data structure and improves code maintainability.
12. Explain the use of MOVE statement in COBOL.
MOVE transfers data from source to destination fields with automatic format conversion when needed.
What an ideal candidate should discuss: Data conversion rules and truncation behavior when moving between different data types and sizes.
13. What is the purpose of FILE-CONTROL paragraph?
FILE-CONTROL maps logical COBOL file names to physical datasets and defines file organization and access methods.
What an ideal candidate should discuss: How FILE-CONTROL enables platform independence by separating logical file definitions from physical implementation.
14. How do you implement loops in COBOL?
COBOL uses PERFORM with various options for repetitive processing:
What an ideal candidate should discuss: Different PERFORM variations (UNTIL, TIMES, VARYING) and their appropriate use cases.
15. What are COBOL copybooks and their benefits?
Copybooks are reusable code segments included in programs using COPY statements. They promote code standardization and reduce maintenance effort.
What an ideal candidate should discuss: How copybooks improve consistency across programs and simplify maintenance of common data structures.
16. Explain the concept of OCCURS DEPENDING ON.
OCCURS DEPENDING ON creates variable-length tables where the actual size depends on a numeric field value.
What an ideal candidate should discuss: Memory efficiency benefits and complexity considerations when working with variable-length structures.
17. What is the difference between STOP RUN and GOBACK?
STOP RUN terminates the entire program execution. GOBACK returns control to the calling program or system, allowing for program chaining.
What an ideal candidate should discuss: When to use each statement based on program architecture and calling conventions.
18. How do you handle numeric operations in COBOL?
COBOL provides arithmetic verbs (ADD, SUBTRACT, MULTIPLY, DIVIDE, COMPUTE) with automatic precision handling.
What an ideal candidate should discuss: Precision considerations and the importance of proper field sizing to avoid truncation.
19. What are condition names and how are they used?
Condition names (level 88) provide meaningful names for specific field values, improving code readability.
What an ideal candidate should discuss: How condition names eliminate magic numbers and improve code self-documentation.
20. What is the purpose of the LINKAGE SECTION?
LINKAGE SECTION defines parameters passed from calling programs, enabling data sharing between program modules.
What an ideal candidate should discuss: Parameter passing mechanisms and the importance of proper data synchronization between calling and called programs.
Did you know?
Grace Hopper, a U.S. Navy Rear Admiral, was one of COBOL’s pioneers and is often called the “Grandmother of COBOL.”
20 Intermediate COBOL Interview Questions with Answers
21. How do you implement error handling in COBOL programs?
Error handling uses file status codes, declarative sections, and USE statements to manage runtime errors gracefully.
What an ideal candidate should discuss: Comprehensive error handling strategies including file status checking, declarative procedures, and graceful failure recovery.
22. Explain the concept of index vs subscript in table processing.
Indexes are binary displacement values optimized for hardware addressing. Subscripts are occurrence numbers converted at runtime.
What an ideal candidate should discuss: Performance differences and when to use SET vs MOVE for index manipulation, plus the efficiency benefits of indexes in large table processing.
23. How do you optimize COBOL program performance?
Key optimization techniques include:
Using indexed files for random access
Minimizing I/O operations through buffering
Employing binary (COMP) fields for calculations
Optimizing table search algorithms
Using inline PERFORM statements
What an ideal candidate should discuss: Specific examples of performance bottlenecks they've encountered and resolved, with quantifiable improvements.
24. What is the difference between static and dynamic CALL?
Static CALL links subprograms at compile time, creating a single load module. Dynamic CALL loads subprograms at runtime, allowing for more flexible program structure.
What an ideal candidate should discuss: Memory usage implications, performance trade-offs, and scenarios where each approach is preferable.
25. How do you implement string manipulation in COBOL?
COBOL provides STRING, UNSTRING, and INSPECT verbs for text processing.
What an ideal candidate should discuss: Delimiter handling, overflow conditions, and performance considerations for large text processing operations.
26. Explain the use of SORT and MERGE statements.
SORT arranges records in specified order. MERGE combines pre-sorted files into a single sorted output.
What an ideal candidate should discuss: INPUT/OUTPUT procedures for data transformation during sort operations and memory management for large datasets.
27. What are the different types of PERFORM statements?
PERFORM paragraph-name: Execute once
PERFORM n TIMES: Execute n iterations
PERFORM UNTIL condition: Loop with condition check
PERFORM VARYING: Complex loop with index manipulation
What an ideal candidate should discuss: Appropriate use cases for each type and performance implications of different loop structures.
28. How do you handle variable-length records in COBOL?
Variable-length records use RECORD CONTAINS clause with minimum and maximum sizes, often with length fields.
What an ideal candidate should discuss: Storage efficiency benefits and complexity of managing variable-length data structures in batch processing.
29. What is the purpose of the EVALUATE statement?
EVALUATE provides multi-way branching similar to switch statements in other languages, offering clearer logic than nested IF statements.
What an ideal candidate should discuss: When EVALUATE is preferable to IF-ELSE chains and its impact on code maintainability.
30. How do you implement transaction processing in COBOL?
Transaction processing uses COMMIT and ROLLBACK concepts, often integrated with database systems or transaction monitors like CICS.
What an ideal candidate should discuss: ACID properties implementation and recovery procedures for maintaining data integrity in business-critical systems.
31. What is the difference between OPEN INPUT and OPEN I-O?
OPEN INPUT allows only reading operations. OPEN I-O permits both read and write operations on the same file within a program.
What an ideal candidate should discuss: File locking implications and when to use each mode based on concurrent access requirements.
32. How do you handle packed decimal (COMP-3) arithmetic?
COMP-3 stores two digits per byte (except the last byte which includes the sign), providing space efficiency for numeric calculations.
What an ideal candidate should discuss: Storage calculations, performance benefits in arithmetic operations, and conversion overhead when interfacing with other systems.
33. Explain the concept of program modularity in COBOL.
Modularity is achieved through subprograms, copybooks, and well-structured paragraph organization, promoting code reuse and maintainability.
What an ideal candidate should discuss: Design patterns they use for creating maintainable COBOL applications and their experience with program libraries.
34. What are the considerations for COBOL program testing?
Testing requires comprehensive data preparation, boundary condition validation, and file status verification across all execution paths.
What an ideal candidate should discuss: Testing methodologies they use, including unit testing approaches and debugging techniques for batch programs.
35. How do you implement data validation in COBOL?
Data validation uses conditional logic, INSPECT statements, and business rule checking to ensure data integrity.
What an ideal candidate should discuss: Comprehensive validation strategies and how they balance performance with data quality requirements.
36. What is the role of JCL in COBOL program execution?
JCL (Job Control Language) defines job execution parameters, file allocations, and system resources for COBOL program execution on mainframes.
What an ideal candidate should discuss: Their experience with JCL debugging and optimization for batch processing efficiency.
37. How do you handle date arithmetic in COBOL?
Date arithmetic often uses intrinsic functions like DATE-OF-INTEGER and INTEGER-OF-DATE for calculations.
What an ideal candidate should discuss: Y2K considerations, different date formats, and leap year handling in business calculations.
38. What is the purpose of the REPLACING clause in COPY statements?
REPLACING allows text substitution when copying code, enabling parameterized copybooks for different contexts.
What an ideal candidate should discuss: How they use REPLACING for maintaining similar programs with different parameters or field names.
39. How do you implement logging and auditing in COBOL programs?
Logging uses dedicated output files with timestamp and transaction details for audit trail maintenance.
What an ideal candidate should discuss: Their approach to logging strategy, including performance impact and audit requirements for regulatory compliance.
40. What are the challenges of COBOL program maintenance?
Key challenges include understanding legacy code, managing dependencies, ensuring backward compatibility, and finding skilled developers.
What an ideal candidate should discuss: Specific maintenance projects they've completed and strategies for documenting and modernizing legacy code.
Did you know?
95% of ATM transactions still rely on COBOL code running in the background.
20 Advanced COBOL Interview Questions with Answers
41. How do you implement multi-threading in COBOL environments?
Multi-threading in COBOL typically involves IBM's Language Environment or Enterprise COBOL features, enabling concurrent processing within a single program.
What an ideal candidate should discuss: Their experience with threaded COBOL applications, synchronization mechanisms, and the complexities of shared data access in concurrent processing.
42. Explain advanced table handling techniques for large datasets.
Advanced techniques include binary search algorithms, multi-dimensional tables, and memory management strategies for processing large volumes of data efficiently.
What an ideal candidate should discuss: Performance optimization techniques for large table operations and memory management strategies for handling datasets that exceed available storage.
43. How do you integrate COBOL with modern web services and APIs?
Integration involves using middleware solutions, web service enablement tools, or COBOL-to-Java bridges to expose COBOL functionality as REST services.
What an ideal candidate should discuss: Specific tools and frameworks they've used, data marshalling challenges, and security considerations when exposing legacy systems to modern interfaces.
44. What are the strategies for COBOL application modernization?
Modernization strategies include:
Refactoring for maintainability
Service-oriented architecture (SOA) implementation
Cloud migration approaches
Integration with modern databases
User interface modernization
What an ideal candidate should discuss: Actual modernization projects they've led, including the business case, technical challenges, and measured outcomes.
45. How do you implement complex business rules in COBOL?
Complex business rules require structured design using decision tables, rule engines, or parameterized processing logic that can be modified without code changes.
What an ideal candidate should discuss: Their approach to making business logic configurable and maintainable, including examples of complex rule implementations.
46. Explain performance tuning techniques for COBOL batch programs.
Performance tuning involves:
I/O optimization through blocking factors
Memory usage optimization
Algorithm efficiency improvements
Database access pattern optimization
System resource utilization analysis
What an ideal candidate should discuss: Specific performance problems they've diagnosed and resolved, with quantifiable improvements and monitoring techniques used.
47. How do you handle COBOL program security and compliance requirements?
Security involves access control implementation, data encryption for sensitive information, audit logging, and compliance with regulatory standards like SOX or PCI-DSS.
What an ideal candidate should discuss: Their experience with security audits, encryption implementation, and compliance reporting requirements.
48. What is your approach to COBOL code refactoring and restructuring?
Refactoring involves identifying code smells, improving program structure, eliminating redundancy, and enhancing maintainability while preserving functionality.
What an ideal candidate should discuss: Systematic approaches they use for refactoring, including testing strategies to ensure functionality preservation.
49. How do you implement disaster recovery for COBOL systems?
Disaster recovery involves backup strategies, system replication, recovery procedures, and business continuity planning for mission-critical COBOL applications.
What an ideal candidate should discuss: Their experience with actual disaster recovery scenarios and the testing procedures they use to validate recovery capabilities.
50. What are the considerations for COBOL application scalability?
Scalability considerations include horizontal vs vertical scaling options, workload distribution strategies, and architectural patterns that support growth.
What an ideal candidate should discuss: Scaling challenges they've addressed and architectural decisions made to support increased transaction volumes.
51. How do you handle version control and change management for COBOL systems?
Version control requires specialized tools that handle COBOL source management, copybook dependencies, and JCL coordination across development teams.
What an ideal candidate should discuss: Tools and processes they use for source code management and their approach to coordinating changes across interdependent programs.
52. What is your experience with COBOL compiler optimization options?
Compiler optimization involves understanding various options that affect performance, memory usage, and compatibility across different COBOL implementations.
What an ideal candidate should discuss: Specific optimization flags they use and the performance impact measurements they've documented.
53. How do you implement data archiving strategies for COBOL systems?
Data archiving requires careful planning of retention policies, access patterns, and regulatory requirements while maintaining system performance.
What an ideal candidate should discuss: Archiving projects they've implemented and the balance between storage costs and data accessibility requirements.
54. What are your strategies for COBOL team leadership and knowledge transfer?
Leadership involves mentoring junior developers, establishing coding standards, and ensuring knowledge transfer from experienced developers.
What an ideal candidate should discuss: Their experience building COBOL teams and the training programs they've implemented for knowledge transfer.
55. How do you handle COBOL system integration with cloud platforms?
Cloud integration involves containerization strategies, data migration approaches, and hybrid architecture implementations that leverage cloud capabilities.
What an ideal candidate should discuss: Actual cloud migration projects they've led and the technical challenges encountered in hybrid implementations.
56. What is your approach to COBOL application monitoring and observability?
Modern monitoring requires implementing logging, metrics collection, and alerting systems for COBOL applications in contemporary IT environments.
What an ideal candidate should discuss: Monitoring solutions they've implemented and how they provide visibility into COBOL application performance and health.
57. How do you implement automated testing for COBOL programs?
Automated testing involves unit test frameworks, data preparation automation, and continuous integration practices adapted for COBOL development.
What an ideal candidate should discuss: Testing frameworks they've used and their approach to implementing CI/CD pipelines for COBOL applications.
58. What are the considerations for COBOL database migration projects?
Database migration involves data mapping, conversion procedures, testing strategies, and rollback planning for moving between different database systems.
What an ideal candidate should discuss: Migration projects they've led and the techniques used to ensure data integrity during the transition process.
59. How do you handle regulatory compliance in COBOL financial systems?
Compliance requires understanding regulatory requirements, implementing audit controls, and maintaining documentation for financial reporting standards.
What an ideal candidate should discuss: Their experience with regulatory audits and the controls they've implemented to ensure compliance.
60. What is your vision for the future of COBOL in enterprise systems?
This requires understanding current trends, modernization approaches, and the evolving role of COBOL in contemporary enterprise architectures.
What an ideal candidate should discuss: Their strategic thinking about COBOL's evolution and their recommendations for organizations maintaining COBOL systems.
Technical Coding Questions with Answers in COBOL
61. Write a COBOL program to calculate compound interest.
What an ideal candidate should discuss: Precision handling for financial calculations and validation of input parameters.
62. Create a program to sort an internal table using COBOL.
What an ideal candidate should discuss: Algorithm efficiency considerations and when to use internal sorting vs external SORT verb.
63. Write a validation routine for employee data.
What an ideal candidate should discuss: Comprehensive validation strategies and error message standardization across the application.
64. Implement a file matching routine between two sequential files.
What an ideal candidate should discuss: File matching algorithms and handling of unmatched records in batch processing scenarios.
65. Create a dynamic table allocation program.
What an ideal candidate should discuss: Memory efficiency benefits and runtime considerations for variable-size data structures.
COBOL Questions for Engineers
71. How do you implement automated testing frameworks for COBOL programs?
Automated testing requires test data generation, expected result validation, and integration with CI/CD pipelines using tools like JUnit for COBOL or custom testing frameworks.
What an ideal candidate should discuss: Testing frameworks they've implemented and their approach to maintaining test suites for legacy COBOL applications.
72. What's your strategy for regression testing COBOL applications?
Regression testing involves maintaining comprehensive test datasets, automating execution of test scenarios, and comparing results across different versions of programs.
What an ideal candidate should discuss: Their experience with regression testing challenges and techniques for ensuring comprehensive coverage of business scenarios.
73. How do you handle test data management for COBOL testing?
Test data management requires creating representative datasets, masking sensitive information, and maintaining data consistency across different test environments.
What an ideal candidate should discuss: Data privacy considerations and techniques for generating realistic test data that covers edge cases.
74. What approaches do you use for performance testing COBOL batch programs?
Performance testing involves measuring execution times, resource utilization, and throughput under various load conditions with comprehensive monitoring.
What an ideal candidate should discuss: Performance bottlenecks they've identified and the tools they use for performance measurement and analysis.
75. How do you implement continuous integration for COBOL development?
CI implementation requires version control integration, automated compilation, testing execution, and deployment coordination across mainframe environments.
What an ideal candidate should discuss: CI/CD pipelines they've built and the challenges of implementing DevOps practices in mainframe environments.
76. How would you integrate machine learning models with COBOL systems?
ML integration involves creating APIs or middleware that allow COBOL programs to consume predictions, implementing data preprocessing, and handling model responses.
What an ideal candidate should discuss: Their vision for combining traditional COBOL processing with modern AI capabilities and potential use cases for AI-enhanced COBOL applications.
77. What's your approach to implementing natural language processing in COBOL environments?
NLP integration typically involves external service calls or preprocessing data for consumption by NLP models, with results integrated back into COBOL business logic.
What an ideal candidate should discuss: Practical applications where NLP could enhance COBOL-based business processes and integration architecture considerations.
78. How do you handle data preparation for machine learning using COBOL?
Data preparation involves extracting, cleaning, and formatting COBOL-maintained data for ML model training, including feature engineering and data quality assurance.
What an ideal candidate should discuss: Their understanding of data pipeline architecture and the role COBOL systems play in providing training data for ML models.
79. What strategies would you use for implementing predictive analytics in COBOL applications?
Predictive analytics integration involves consuming model predictions within business logic, implementing threshold-based decision making, and maintaining audit trails.
What an ideal candidate should discuss: Business scenarios where predictive capabilities could enhance traditional COBOL processing and implementation approaches.
80. How do you envision AI-assisted COBOL code generation and maintenance?
AI assistance could involve code pattern recognition, automated refactoring suggestions, and intelligent code completion for COBOL development environments.
What an ideal candidate should discuss: Their perspective on AI tools for COBOL development and the potential for AI to address the COBOL skills shortage challenge.
Did you know?
During the COVID-19 pandemic, U.S. states scrambled to find COBOL programmers to update unemployment systems.
15 Key Questions with Answers to Ask Freshers and Juniors
81. Can you explain what COBOL stands for and its primary purpose?
COBOL stands for Common Business-Oriented Language. It was designed for business data processing and is still widely used in financial, government, and administrative systems.
What an ideal candidate should discuss: Basic understanding of COBOL's business orientation and its continued relevance in enterprise systems.
82. What are the four main divisions of a COBOL program?
The four divisions are Identification (program metadata), Environment (system configuration), Data (variable definitions), and Procedure (executable logic).
What an ideal candidate should discuss: How each division serves a specific purpose in program organization and documentation.
83. How do you define a simple variable in COBOL?
Variables are defined using level numbers and PICTURE clauses: 01 EMPLOYEE-NAME PIC X(30).
What an ideal candidate should discuss: Basic syntax understanding and the importance of meaningful variable names.
84. What is the difference between PIC X and PIC 9?
PIC X defines alphanumeric data, while PIC 9 defines numeric data. The number in parentheses specifies the field length.
What an ideal candidate should discuss: Basic data type concepts and when to use each type.
85. How do you display output in COBOL?
Output is displayed using the DISPLAY statement: DISPLAY "Hello World" or DISPLAY VARIABLE-NAME.
What an ideal candidate should discuss: Basic I/O concepts and formatting considerations.
86. What is the purpose of the WORKING-STORAGE SECTION?
WORKING-STORAGE SECTION defines temporary variables and constants used within the program that retain their values throughout execution.
What an ideal candidate should discuss: Understanding of variable scope and lifetime in COBOL programs.
87. How do you implement a simple IF condition in COBOL?
What an ideal candidate should discuss: Basic conditional logic and the importance of END-IF statements.
88. What is the MOVE statement used for?
MOVE transfers data from one field to another with automatic format conversion: MOVE "John" TO EMPLOYEE-NAME.
What an ideal candidate should discuss: Basic data movement concepts and understanding of automatic conversions.
89. How do you create a simple loop in COBOL?
Loops use PERFORM statements: PERFORM DISPLAY-RECORD 10 TIMES or PERFORM UNTIL END-OF-FILE.
What an ideal candidate should discuss: Basic iteration concepts and different loop types available.
90. What is the significance of level numbers in data definition?
Level numbers (01-49) define data hierarchy and relationships, with 01 being record level and higher numbers being subordinate items.
What an ideal candidate should discuss: Basic data structure concepts and hierarchical organization.
91. How do you handle end-of-file conditions?
End-of-file is handled using AT END clause with READ statements or by checking file status codes.
What an ideal candidate should discuss: Basic file processing concepts and error handling awareness.
92. What is a copybook in COBOL?
A copybook contains reusable code that can be included in programs using the COPY statement, promoting code standardization.
What an ideal candidate should discuss: Code reuse concepts and maintenance benefits of copybooks.
93. How do you define a table (array) in COBOL?
Tables use the OCCURS clause: 01 MONTH-NAMES. 05 MONTH PIC X(10) OCCURS 12 TIMES.
What an ideal candidate should discuss: Basic array concepts and accessing table elements.
94. What is the difference between PERFORM and CALL?
PERFORM executes internal procedures within the same program, while CALL invokes external programs.
What an ideal candidate should discuss: Basic program structure and modularization concepts.
95. How do you handle numeric calculations in COBOL?
Numeric calculations use arithmetic verbs like ADD, SUBTRACT, MULTIPLY, DIVIDE, or the COMPUTE statement.
What an ideal candidate should discuss: Basic arithmetic operations and when to use each approach.
15 Key Questions with Answers to Ask Seniors and Experienced
96. Describe your experience leading COBOL modernization projects.
Senior candidates should discuss specific modernization initiatives, including business justification, technical approach, team management, and measurable outcomes.
What an ideal candidate should discuss: Leadership experience, technical decision-making, and ability to balance modernization with system stability requirements.
97. How do you approach architecture decisions for large-scale COBOL systems?
Architecture decisions require considering scalability, maintainability, integration requirements, and long-term business needs while managing technical debt.
What an ideal candidate should discuss: Strategic thinking, experience with enterprise architecture, and ability to make technology decisions that align with business objectives.
98. What's your strategy for building and mentoring COBOL development teams?
Team building involves recruiting talent, establishing development standards, implementing training programs, and ensuring knowledge transfer from experienced developers.
What an ideal candidate should discuss: Leadership and mentoring experience, including specific programs they've implemented for skill development and knowledge retention.
99. How do you handle vendor management and tool selection for COBOL environments?
Vendor management requires evaluating tools, negotiating contracts, managing relationships, and ensuring tools meet technical and business requirements.
What an ideal candidate should discuss: Experience with vendor evaluation processes and their approach to technology selection that balances cost, functionality, and strategic alignment.
100. Describe your experience with regulatory compliance in COBOL systems.
Compliance experience should include specific regulations (SOX, PCI-DSS, etc.), audit preparation, control implementation, and compliance reporting.
What an ideal candidate should discuss: Detailed compliance experience and their approach to maintaining compliance while managing system changes and modernization initiatives.
101. How do you manage technical debt in legacy COBOL applications?
Technical debt management requires systematic assessment, prioritization frameworks, refactoring strategies, and balancing debt reduction with feature development.
What an ideal candidate should discuss: Frameworks they use for debt assessment and their success in convincing management to invest in debt reduction initiatives.
102. What's your approach to disaster recovery planning for COBOL systems?
DR planning involves backup strategies, recovery procedures, testing protocols, and business continuity considerations for mission-critical COBOL applications.
What an ideal candidate should discuss: Actual disaster recovery experiences and their approach to balancing recovery time objectives with cost considerations.
103. How do you implement DevOps practices in COBOL environments?
DevOps implementation requires adapting modern practices to mainframe environments, including CI/CD pipelines, automated testing, and deployment automation.
What an ideal candidate should discuss: Specific DevOps transformations they've led and the challenges of implementing modern practices in traditional environments.
104. Describe your experience with COBOL system integration projects.
Integration projects require API development, middleware selection, data mapping, and coordination between different technology teams.
What an ideal candidate should discuss: Complex integration scenarios they've managed and their approach to ensuring data consistency across integrated systems.
105. How do you approach budgeting and resource planning for COBOL projects?
Resource planning involves cost estimation, skill assessment, timeline development, and risk management for COBOL development initiatives.
What an ideal candidate should discuss: Budget management experience and their approach to justifying COBOL investments to business stakeholders.
106. What's your strategy for managing COBOL application security?
Security management requires threat assessment, access control implementation, vulnerability management, and security audit coordination.
What an ideal candidate should discuss: Security frameworks they've implemented and their experience managing security in regulated environments.
107. How do you handle stakeholder communication for COBOL projects?
Stakeholder communication requires translating technical concepts for business audiences, managing expectations, and maintaining project visibility.
What an ideal candidate should discuss: Communication strategies they use and their success in building business support for COBOL initiatives.
108. Describe your experience with COBOL performance optimization at scale.
Performance optimization requires system-level analysis, resource utilization management, and coordination with infrastructure teams.
What an ideal candidate should discuss: Large-scale optimization projects and quantifiable performance improvements they've achieved.
109. How do you manage change control in critical COBOL systems?
Change control requires rigorous testing procedures, rollback planning, impact assessment, and coordination with business operations.
What an ideal candidate should discuss: Change management processes they've implemented and their approach to balancing system stability with business needs.
110. What's your vision for the future of COBOL in your organization?
Strategic vision should include modernization roadmaps, skill development plans, integration strategies, and alignment with business objectives.
What an ideal candidate should discuss: Strategic thinking about COBOL's role in the organization's technology landscape and their recommendations for long-term sustainability.
5 Scenario-based Questions with Answers
111. Your company's critical payroll system written in COBOL crashes during month-end processing. How do you handle this crisis?
Immediate Response:
Activate incident response procedures
Assess data integrity and determine last successful checkpoint
Implement emergency rollback procedures if necessary
Communicate with stakeholders about impact and recovery timeline
Root Cause Analysis:
Review system logs and error messages
Analyze resource utilization and system performance
Check for data corruption or file system issues
Examine recent changes that might have caused the failure
Recovery Strategy:
Restore from last known good backup
Implement data recovery procedures
Validate data integrity before resuming processing
Execute comprehensive testing before returning to production
What an ideal candidate should discuss: Crisis management experience, systematic troubleshooting approach, and communication skills under pressure.
112. A major client wants to integrate their new cloud-based CRM with your 30-year-old COBOL customer management system. Design the integration approach.
Technical Architecture:
API gateway for secure communication
Data transformation middleware for format conversion
Real-time synchronization vs batch processing decision
Error handling and retry mechanisms
Data Mapping:
Field-level mapping between systems
Data validation and cleansing procedures
Handling of data type differences
Master data management strategy
Implementation Plan:
Phased rollout approach
Comprehensive testing strategy
Fallback procedures
Performance monitoring
What an ideal candidate should discuss: Integration architecture experience, project management skills, and understanding of both legacy and modern systems.
113. Your COBOL development team is losing experienced developers to retirement. How do you ensure business continuity?
Knowledge Transfer Strategy:
Document critical business logic and system dependencies
Create comprehensive system documentation
Record video walkthroughs of complex procedures
Establish mentorship programs with remaining staff
Talent Acquisition:
Partner with universities offering COBOL programs
Implement COBOL training programs for existing developers
Consider contract developers for specific projects
Evaluate offshore development options
System Modernization:
Assess modernization vs maintenance trade-offs
Implement tools that reduce maintenance complexity
Consider gradual migration to more maintainable platforms
Invest in development tools that improve productivity
What an ideal candidate should discuss: Workforce planning experience, knowledge management strategies, and business continuity planning.
114. A security audit reveals vulnerabilities in your COBOL applications. Develop a remediation plan.
Vulnerability Assessment:
Catalog all identified security issues
Prioritize vulnerabilities by risk level
Assess impact on business operations
Determine remediation complexity and effort
Remediation Strategy:
Implement access control improvements
Add encryption for sensitive data
Enhance audit logging capabilities
Update authentication mechanisms
Compliance Alignment:
Map fixes to regulatory requirements
Implement control testing procedures
Establish ongoing monitoring processes
Create compliance documentation
What an ideal candidate should discuss: Security expertise, regulatory compliance experience, and project management skills for sensitive initiatives.
115. Your organization needs to process 10x more transaction volume, but the current COBOL system is at capacity. What's your scaling strategy?
Capacity Analysis:
Identify current bottlenecks (CPU, I/O, memory)
Analyze transaction patterns and peak loads
Assess infrastructure constraints
Evaluate application efficiency opportunities
Scaling Options:
Horizontal scaling through parallel processing
Vertical scaling through hardware upgrades
Application optimization and tuning
Database performance improvements
Architecture Evolution:
Implement load balancing strategies
Consider microservices extraction
Evaluate cloud deployment options
Plan for future growth requirements
What an ideal candidate should discuss: Performance analysis skills, scalability architecture experience, and ability to balance technical solutions with business requirements.
Did you know?
COBOL is known for being so verbose that a single program can read like an English novel.
Common Interview Mistakes to Avoid
For Interviewers:
Focusing Only on Syntax Knowledge: Don't limit questions to COBOL syntax memorization. Assess problem-solving abilities and business logic understanding.
Ignoring Modern Integration Skills: Avoid exclusively focusing on traditional COBOL. Evaluate candidates' ability to work with modern systems and technologies.
Overlooking Communication Skills: Don't underestimate the importance of communication. COBOL developers often need to explain complex legacy systems to non-technical stakeholders.
Assuming All COBOL Experience is Equal: Different COBOL environments (mainframe, distributed, cloud) require different skill sets. Tailor questions to your specific environment.
Neglecting Cultural Fit Assessment: Don't ignore soft skills. COBOL projects often involve long-term maintenance relationships and team collaboration.
For Candidates:
Being Dismissive of Modern Technologies: Don't present yourself as only interested in legacy systems. Show enthusiasm for learning modern integration approaches.
Overemphasizing Years of Experience: Don't rely solely on tenure. Demonstrate continuous learning and adaptation to changing requirements.
Providing Generic Answers: Avoid cookie-cutter responses. Use specific examples from your experience to illustrate your capabilities.
Ignoring Business Context: Don't focus only on technical details. Show understanding of how COBOL systems support business operations.
Failing to Ask Questions: Don't miss the opportunity to assess the role. Ask about modernization plans, team structure, and growth opportunities.
12 Key Questions with Answers Engineering Teams Should Ask
116. How do you ensure code quality and maintainability in COBOL programs?
Quality assurance involves establishing coding standards, implementing peer review processes, creating comprehensive documentation, and using static analysis tools where available.
What engineering teams should look for: Systematic approaches to quality management and experience with maintaining large codebases over extended periods.
117. What's your approach to technical documentation for COBOL systems?
Documentation should include system architecture, business logic explanation, data flow diagrams, and operational procedures that enable knowledge transfer and system maintenance.
What engineering teams should look for: Documentation standards and experience creating materials that help other developers understand complex systems.
118. How do you handle debugging complex COBOL programs in production?
Debugging involves systematic log analysis, trace facility usage, dump analysis, and coordination with operations teams while minimizing business impact.
What engineering teams should look for: Debugging methodology and experience resolving production issues under pressure.
119. What's your strategy for implementing automated testing in COBOL environments?
Automated testing requires test data management, expected result validation, regression test execution, and integration with development workflows.
What engineering teams should look for: Testing experience and understanding of quality assurance processes for business-critical systems.
120. How do you approach performance monitoring and optimization?
Performance management involves establishing baseline metrics, identifying bottlenecks, implementing monitoring solutions, and optimizing resource utilization.
What engineering teams should look for: Performance analysis skills and experience with monitoring tools and optimization techniques.
121. What's your experience with version control and change management for COBOL?
Version control requires specialized tools for COBOL source management, coordinating copybook changes, and managing dependencies across programs.
What engineering teams should look for: Source code management experience and understanding of change control processes in regulated environments.
122. How do you handle integration testing for COBOL systems?
Integration testing involves end-to-end workflow validation, interface testing, data consistency verification, and coordination with multiple system teams.
What engineering teams should look for: Testing methodology and experience coordinating testing across complex system landscapes.
123. What's your approach to incident response for COBOL applications?
Incident response requires systematic troubleshooting, stakeholder communication, root cause analysis, and implementation of preventive measures.
What engineering teams should look for: Crisis management experience and systematic problem-solving approaches under pressure.
124. How do you manage technical debt in COBOL applications?
Technical debt management involves identifying areas needing improvement, prioritizing remediation efforts, and balancing maintenance with feature development.
What engineering teams should look for: Strategic thinking about system maintenance and experience managing competing priorities.
125. What's your experience with COBOL development tooling and environments?
Development environment management includes IDE configuration, compiler options, debugging tools, and integration with testing frameworks.
What engineering teams should look for: Tool proficiency and experience optimizing development workflows for team productivity.
126. How do you ensure security best practices in COBOL development?
Security practices involve access control implementation, sensitive data handling, audit logging, and compliance with security standards.
What engineering teams should look for: Security awareness and experience implementing security controls in business-critical applications.
127. What's your approach to knowledge sharing and team collaboration?
Knowledge sharing involves documentation creation, mentoring programs, code review participation, and cross-training initiatives.
What engineering teams should look for: Collaboration skills and commitment to team knowledge development and sustainability.
The 80/20 - What Key Aspects You Should Assess During Interviews
Core Technical Skills (40%)
COBOL Language Proficiency: Syntax understanding, data handling, file processing
System Integration: API development, database connectivity, middleware usage
Performance Optimization: Bottleneck identification, tuning techniques, resource management
Problem-Solving Ability (25%)
Analytical Thinking: Breaking down complex problems into manageable components
Debugging Skills: Systematic troubleshooting approach and root cause analysis
Solution Architecture: Designing maintainable and scalable solutions
Business Understanding (20%)
Domain Knowledge: Understanding of business processes and regulatory requirements
Impact Assessment: Ability to evaluate technical decisions on business operations
Stakeholder Communication: Translating technical concepts for business audiences
Modernization Mindset (15%)
Integration Skills: Connecting legacy systems with modern platforms
Learning Agility: Adapting to new technologies and development practices
Future Vision: Strategic thinking about COBOL's evolution in the organization
Focus Areas for Different Roles:
Junior Developers: Emphasize core technical skills and learning potential
Senior Developers: Balance technical depth with business understanding and leadership
Architects: Prioritize solution design and modernization strategy
Team Leads: Focus on communication skills and team development capabilities
Main Red Flags to Watch Out for
Technical Red Flags
Inability to Explain Basic Concepts: Difficulty articulating fundamental COBOL concepts or data structures
Over-Reliance on Memorization: Focusing on syntax memorization without understanding underlying principles
Resistance to Modern Practices: Dismissing contemporary development practices like version control or automated testing
Poor Problem-Solving Approach: Lack of systematic methodology for debugging or issue resolution
Communication Red Flags
Cannot Explain Technical Concepts Simply: Inability to communicate technical information to non-technical stakeholders
Dismissive of Business Requirements: Showing little interest in understanding business context or user needs
Poor Documentation Habits: History of creating inadequate or no documentation for their work
Inflexibility in Team Settings: Difficulty working collaboratively or accepting feedback
Experience Red Flags
Limited Scope of Experience: Only worked in narrow technical areas without broader system understanding
No Modernization Experience: Never worked on integration projects or system updates
Avoidance of Complex Projects: History of avoiding challenging assignments or responsibilities
No Continuous Learning: Lack of recent skill development or technology exploration
Attitude Red Flags
"Legacy System" Mentality: Treating COBOL systems as outdated rather than valuable business assets
Resistance to Change: Unwillingness to adapt to new requirements or technologies
Blame-Focused Mindset: Tendency to blame systems, processes, or other people for problems
Lack of Ownership: Not taking responsibility for code quality or system reliability
Did you know?
COBOL once stood for “Common Business-Oriented Language”, and it still lives up to its name.
Don’t let retiring COBOL talent leave your systems vulnerable.
Utkrusht helps you find developers who understand mainframes, modernization, and mission-critical reliability. Get started now and future-proof your business.
Founder, Utkrusht AI
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