NCA-GENL Software Development Practice Question
A developer is using the NVIDIA API Catalog to test a Llama-3 model via its API endpoint. They need to send a request that includes a system prompt to set the model's behavior. Which component of the request payload is used to provide the system prompt?
⚠ Common exam trap
The trap here is assuming a top-level `system` field or a special header, rather than using the standard `messages` array with a system role.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
A message with `role` set to `system` within the `messages` array.
In the NVIDIA API Catalog, chat models accept a `messages` array where each message has a `role` and `content`. To set a system prompt, include a message with `role` set to `system`. This is consistent with common chat completion APIs and ensures the model treats the content as a system-level instruction that guides its responses throughout the conversation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
A message with `role` set to `system` within the `messages` array.
Why this is correct
The NVIDIA API Catalog endpoints for chat models expect a `messages` array containing objects with `role` and `content`. To provide a system prompt, include a message with `role` set to `system` and the desired instruction in `content`. This is a standard format for chat-based LLM APIs and ensures the model interprets the instruction as a system-level directive.
- ✗
The `prompt` field, prefixed with `System:` followed by the instruction.
Why it's wrong here
While some completion APIs use a single `prompt` string, the NVIDIA API Catalog's chat endpoints use a structured `messages` array. Prefixing a `prompt` with `System:` is not the documented method and may not be parsed correctly. The correct approach is to use the `messages` array with a system role message.
- ✗
The `system` field at the top level of the JSON payload.
Why it's wrong here
The NVIDIA API Catalog does not use a top-level `system` field. The API follows a chat completion format similar to OpenAI, where system prompts are part of the `messages` array. A top-level `system` field would be ignored, and the model would not receive the intended instruction.
- ✗
The `instructions` parameter in the request headers.
Why it's wrong here
The NVIDIA API Catalog does not support an `instructions` parameter in headers. System prompts are part of the request body, specifically within the `messages` array. Using headers would not be processed by the API, and the model would not receive the system prompt, leading to unintended behavior.
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Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official NVIDIA exam blueprint
This NCA-GENL practice question is part of Courseiva's free NVIDIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the NCA-GENL exam.