The correct implementation is a 'before' Business Rule that checks if the state is changing to 'Resolved' and if category is empty, then aborts the update with an error message. This works because a before Business Rule runs server-side before the record is saved, allowing you to use gs.addErrorMessage() and return false to halt the transaction, enforcing server-side validation that cannot be bypassed by disabling JavaScript or manipulating network requests. On the ServiceNow Certified Application Developer CAD exam, this question tests your understanding of where validation logic must live—client-side scripts like onChange or onSubmit can be circumvented, while ACLs control access rights, not state transitions, and Data Policies enforce field requirements globally, which would break existing records with empty categories in other states. The common trap is choosing a client-side solution because it seems simpler, but remember: any validation that protects data integrity must be enforced server-side. Memory tip: "Before Business Rule, before the save—catch the bad data at the server gate."
SNOW-CAD Core Application Development Practice Question
This SNOW-CAD practice question tests your understanding of core application development. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A company has a requirement that the 'state' field of an incident cannot be changed from 'In Progress' to 'Resolved' if the 'category' field is empty. This validation must be enforced server-side to prevent data integrity issues. Which implementation should be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Create a 'before' Business Rule that checks if the state is changing to 'Resolved' and if category is empty, aborts the update with an error message.
Option C is correct because a Business Rule with 'before' 'update' and a condition checking the change, then using gs.addErrorMessage() and returning false, will prevent the update server-side. Option A (Client Script) runs client-side and can be bypassed. Option B (ACL) controls read/write access, not specific value transitions. Option D (Data Policy) makes category mandatory, which conflicts with existing records that might have empty category on other states.
Key principle: ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
Make the 'category' field mandatory using a Data Policy.
Why it's wrong here
Making category mandatory would enforce it on all states, not only for the transition.
✗
Configure an ACL on the 'state' field to deny write access when category is empty.
Why it's wrong here
ACLs control field-level access, not transition validation.
✗
Create a Client Script on 'state' change that checks if category is empty and shows an error message.
Why it's wrong here
Client-side validation can be bypassed by direct API calls or database updates.
✓
Create a 'before' Business Rule that checks if the state is changing to 'Resolved' and if category is empty, aborts the update with an error message.
Why this is correct
Before Business Rules can prevent updates by returning false and setting error messages.
Related concept
Standard ACLs match source addresses.
Common exam traps
Common exam trap: ACLs stop at the first match
ACLs are processed top to bottom. The first matching entry wins, and an implicit deny usually exists at the end.
Detailed technical explanation
How to think about this question
ACL questions test precision: source, destination, protocol, port and direction. A generally correct ACL can still fail if it is applied on the wrong interface or in the wrong direction.
KKey Concepts to Remember
Standard ACLs match source addresses.
Extended ACLs can match source, destination, protocol and ports.
The first matching ACL entry is used.
There is usually an implicit deny at the end.
TExam Day Tips
→Check inbound versus outbound direction.
→Read the ACL from top to bottom.
→Look for a broader permit or deny above the intended line.
Key takeaway
ACLs process entries top to bottom and stop at the first match. Entry order and interface direction matter as much as the permit or deny statement.
Real-world example
How this comes up in practice
A security administrator must allow nursing staff to reach a patient records server while blocking access from the guest Wi-Fi VLAN. After applying an extended ACL, traffic is still blocked from nursing workstations. The ACL was applied outbound instead of inbound on the wrong interface. Questions like this test ACL direction and placement rules.
What to study next
Got this wrong? Here's your next step.
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SNOW-CAD ACL questions on filtering logic and placement.
Core Application Development — This question tests Core Application Development — Standard ACLs match source addresses..
What is the correct answer to this question?
The correct answer is: Create a 'before' Business Rule that checks if the state is changing to 'Resolved' and if category is empty, aborts the update with an error message. — Option C is correct because a Business Rule with 'before' 'update' and a condition checking the change, then using gs.addErrorMessage() and returning false, will prevent the update server-side. Option A (Client Script) runs client-side and can be bypassed. Option B (ACL) controls read/write access, not specific value transitions. Option D (Data Policy) makes category mandatory, which conflicts with existing records that might have empty category on other states.
What should I do if I get this SNOW-CAD question wrong?
Review ACL processing order, placement rules (standard near destination, extended near source), and inbound vs outbound direction. Study wildcard masks and implicit deny. Then practise related SNOW-CAD ACL questions on filtering logic and placement.
What is the key concept behind this question?
Standard ACLs match source addresses.
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