ServiceNow Developer Interview Questions

[Its_Azar]

 

1. Core ServiceNow Platform Fundamentals

1. What is ServiceNow, and how does it differ from traditional web applications?

Interviewers want to assess whether you understand that ServiceNow is not a generic web app, but a low-code enterprise workflow platform.

Key points to explain:

• ServiceNow is built on a single data model using tables

• It provides out-of-the-box ITSM, HR, CSM, GRC, and custom app capabilities

• Developers extend functionality using configuration first, code second

• The platform enforces upgrade-safe development practices

A strong answer connects ServiceNow’s architecture with scalability and maintainability.

 

2. What is an application scope, and why is it important?

This question tests your understanding of modular development.

You should explain:

• What Global scope is

• What Scoped applications are

• How scope controls:

  • Table access

  • Script Include visibility

  • API exposure

• Why scoped apps are safer for upgrades and reuse

Also mention cross-scope access policies and real-world scenarios where incorrect scope design causes issues.

3. Explain the ServiceNow table structure and inheritance model

This question checks your data model understanding.

Topics to cover:

• Base tables (Task, CMDB tables)

• Table extension and inheritance

• Shared fields from parent tables

• Why extending Task is common

• How inheritance impacts:

  • Business Rules

  • ACLs

  • Reporting

Interviewers often follow up with performance-related questions here.

 

2. Client-Side Scripting (UI Behavior)

 

4. What are Client Scripts, and when should they be used?

Explain that Client Scripts:

• Run in the browser

• Improve user experience, not business logic

• Are used for validation, UI changes, and form behavior

Then break down:

• onLoad

• onChange

• onSubmit

• onCellEdit

Also explain what should NOT be done in client scripts, such as data integrity enforcement.

 

5. Difference between Client Script and UI Policy

This is a classic interview question.

Your explanation should include:

• UI Policies are declarative

• Client Scripts are imperative

• Performance considerations

• Maintainability trade-offs

• When Client Scripts are unavoidable

Interviewers appreciate answers that emphasize using UI Policies first where possible.

 

6. How does GlideAjax work?

This is a very important developer question.

Explain:

• Why client scripts cannot directly access the database

• How GlideAjax bridges client and server

• The role of Script Includes

• Why asynchronous calls matter

Avoid code here; focus on flow and design rationale.

 

3. Server-Side Scripting (Core Development Area)

7. What are Business Rules, and how do you decide when to use them?

You should discuss:

• When Business Rules execute

• Different execution timings:

  • Before

  • After

  • Async

  • Display

• Use cases for each type

Also talk about:

• Avoiding unnecessary Business Rules

• Performance impact

• Debugging complexity

This is a place where interviewers check platform maturity.

 

8. Difference between Business Rules, Script Includes, and Flow Designer

This question tests architectural decision-making.

A strong answer explains:

• Business Rules = record lifecycle logic

• Script Includes = reusable logic

• Flow Designer = event-driven workflows

• When code is preferable to flows

• When flows reduce technical debt

Avoid positioning one as “better”; focus on appropriate usage.

 

9. What is a Script Include, and how do you design one properly?

Key points to cover:

• Purpose of Script Includes

• Reusability and encapsulation

• Client-callable vs server-only

• Access modifiers

• Naming conventions

Interviewers often ask follow-ups about performance and maintainability.

 

10. Explain synchronous vs asynchronous Business Rules

Explain:

• Execution timing

• User experience impact

• When async rules are preferred

• Common mistakes developers make with async logic

This question reveals how well you understand transaction processing in ServiceNow.

 

4. Security and Access Control

11. What are ACLs, and how do they work?

Security is non-negotiable.

Your explanation should include:

• Table ACLs

• Field ACLs

• Role-based checks

• Scripted ACLs

• Evaluation order

Also mention:

• Performance considerations

• Why ACLs should be preferred over UI restrictions

 

12. Difference between ACLs and UI Policies

Interviewers want to see if you understand security vs UI control.

Explain clearly:

• UI Policies control visibility

• ACLs control access

• UI restrictions can be bypassed

• ACLs are enforced server-side

This is a foundational security concept.

 

5. Data Handling and APIs

13. What is GlideRecord, and how is it used?

This is unavoidable in developer interviews.

You should explain:

• GlideRecord as an abstraction layer

• CRUD operations

• Query building

• Encoded queries

• Performance best practices

Mention common pitfalls:

• Queries inside loops

• Not limiting results

• Ignoring indexes

 

14. What are REST APIs in ServiceNow, and how have you used them?

Cover:

• Inbound vs outbound REST

• Scripted REST APIs

• Authentication methods

• Error handling

• Real-world integration examples

Interviewers often ask follow-ups on security and payload validation.

 

6. Performance and Best Practices

15. How do you optimize performance in ServiceNow?

This question separates junior developers from experienced ones.

Topics to include:

• Avoiding unnecessary Business Rules

• Using async processing

• Query optimization

• Index usage

• Script Includes over duplicated logic

• Avoiding client-server round trips

Use practical explanations, not theory.

 

16. How do you debug issues in ServiceNow?

Discuss:

• Background Scripts

• Logs

• Script Debugger

• gs.log and gs.info

• System Diagnostics

Interviewers look for methodical debugging approaches, not trial-and-error.

 

7. Update Sets and Deployment

17. What are Update Sets, and what are their limitations?

Explain:

• Purpose of Update Sets

• What gets captured

• What does not get captured

• Best practices for naming and management

• Common migration issues

Mention scenarios where application repository or CI/CD is preferable.

 

18. How do you handle conflicts during deployment?

A strong answer covers:

• Preview issues

• Skipped records

• Manual conflict resolution

• Testing after deployment

• Rollback strategy

This shows real project experience.

 

8. Scenario-Based Questions (Very Important)

19. How would you design a custom application in ServiceNow?

Explain your approach:

• Requirement analysis

• Data model design

• Security planning

• UI design

• Business logic placement

• Testing and deployment

Interviewers want to see structured thinking, not just technical knowledge.

 

20. How do you decide whether to use code or configuration?

This is a mindset question.

Discuss:

• Platform-first approach

• Maintainability

• Upgrade safety

• Team skill levels

• Long-term ownership

This answer often leaves a strong impression.

 

Final Thoughts

ServiceNow development interviews are less about memorizing features and more about understanding why things exist and how to use them correctly.

If you:

• Understand platform fundamentals

• Write clean, reusable server-side logic

• Respect security boundaries

• Think about performance early

• Prefer configuration before code

—you are already ahead of most candidates.