This CISA practice question tests your understanding of information systems acquisition, development and implementation. 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.
An organization is implementing a COTS application. The project team plans to heavily customize the application to meet unique business processes. Which of the following is the most significant risk?
Vendor lock-in
Why wrong: Vendor lock-in is a risk but not the most significant for customization.
Incompatibility with future releases
Why wrong: This is a consequence of upgrade difficulties.
Difficulties in applying future vendor upgrades
Customizations break compatibility with standard upgrades, jeopardizing future support.
High implementation cost
Why wrong: Cost is a concern but not the primary risk.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
Difficulties in applying future vendor upgrades
Option B is correct because heavy customization makes it difficult to apply vendor upgrades, potentially leading to unsupported software. Option A is incorrect while vendor lock-in is a risk, upgrade difficulties are more direct. Option C is incorrect because incompatibility is a symptom of upgrade difficulties. Option D is incorrect because high cost is a secondary concern.
Key principle: NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
Vendor lock-in
Why it's wrong here
Vendor lock-in is a risk but not the most significant for customization.
Incompatibility with future releases
Why it's wrong here
This is a consequence of upgrade difficulties.
Difficulties in applying future vendor upgrades
Why this is correct
Customizations break compatibility with standard upgrades, jeopardizing future support.
Related concept
Static NAT maps one inside address to one outside address.
High implementation cost
Why it's wrong here
Cost is a concern but not the primary risk.
Common exam traps
NAT is not only about the public address. The inside/outside interface roles and the ACL or rule that matches traffic are just as important.
Detailed technical explanation
NAT questions usually test address translation, overload/PAT behaviour, static mappings and whether the right traffic is being translated. Read the interface direction and address terms carefully.
Key takeaway
NAT direction and interface roles matter as much as the IP address mapping. Inside/outside designation controls which traffic is translated.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CISA NAT questions on configuration and troubleshooting.
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FAQ
Information Systems Acquisition, Development and Implementation — This question tests Information Systems Acquisition, Development and Implementation — Static NAT maps one inside address to one outside address..
The correct answer is: Difficulties in applying future vendor upgrades — Option B is correct because heavy customization makes it difficult to apply vendor upgrades, potentially leading to unsupported software. Option A is incorrect while vendor lock-in is a risk, upgrade difficulties are more direct. Option C is incorrect because incompatibility is a symptom of upgrade difficulties. Option D is incorrect because high cost is a secondary concern.
Review the four NAT address types (inside local, inside global, outside local, outside global), PAT port overload, and static vs dynamic NAT use cases. Then practise related CISA NAT questions on configuration and troubleshooting.
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 24, 2026
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