- A
The new RAM modules are not compatible because they are not ECC, while the server requires ECC.
Why wrong: The scenario states the new modules are registered ECC, so this is not the issue.
- B
The server's BIOS needs to be updated to support 128 GB.
Why wrong: If the server originally supported 128 GB (as stated), a BIOS update is unlikely needed. The problem is more specific to the modules themselves.
- C
The new modules have a different number of ranks (e.g., dual-rank vs. single-rank) than the original modules, causing a rank mismatch that the memory controller cannot handle.
Servers are sensitive to rank configuration. Mixing single-rank and dual-rank modules, or using modules with a different number of ranks than the system expects, can prevent POST.
- D
The new modules are not seated properly in the slots.
Why wrong: Improper seating is possible, but given that the original modules work and the new ones all fail, a systematic issue like rank mismatch is more likely.
Quick Answer
The answer is a rank mismatch between the new and original memory modules. Registered ECC DDR4 memory relies on strict rank compatibility per channel; if the server originally used single-rank modules and the new 16 GB sticks are dual-rank, the memory controller may exceed its supported rank count when all eight slots are populated, causing the POST failure. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding that server RAM upgrade fails POST rank compatibility is often due to mixing ranks or overloading the channel’s rank limit, not a simple capacity issue—a common trap is assuming all 16 GB modules are identical. Remember that rank is like lanes on a highway: more ranks per channel can jam the controller, so always verify the rank count in the server’s documentation before upgrading.
220-1201 RAM Practice Question
This 220-1201 practice question tests your understanding of ram. 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 server administrator needs to upgrade a critical database server from 64 GB to 128 GB of RAM. The server uses registered ECC DDR4 memory. They have purchased 8 x 16 GB registered ECC modules. When they install them, the server fails to POST with a memory error. The original 64 GB (4 x 16 GB) modules work fine. What is the most likely reason?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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
The new modules have a different number of ranks (e.g., dual-rank vs. single-rank) than the original modules, causing a rank mismatch that the memory controller cannot handle.
Registered (buffered) ECC memory is designed for servers and has specific compatibility requirements, especially regarding the number of ranks per channel and the memory controller's capabilities. The most likely issue is that the new modules are of a different rank (e.g., dual-rank vs. single-rank) or the server's memory controller cannot handle the total number of ranks when all slots are populated. Mixing ranks or exceeding the rank limit per channel can cause POST failures.
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
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
The new RAM modules are not compatible because they are not ECC, while the server requires ECC.
Why it's wrong here
The scenario states the new modules are registered ECC, so this is not the issue.
- ✗
The server's BIOS needs to be updated to support 128 GB.
Why it's wrong here
If the server originally supported 128 GB (as stated), a BIOS update is unlikely needed. The problem is more specific to the modules themselves.
- ✓
The new modules have a different number of ranks (e.g., dual-rank vs. single-rank) than the original modules, causing a rank mismatch that the memory controller cannot handle.
Why this is correct
Servers are sensitive to rank configuration. Mixing single-rank and dual-rank modules, or using modules with a different number of ranks than the system expects, can prevent POST.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Static NAT maps one inside address to one outside address.
- ✗
The new modules are not seated properly in the slots.
Why it's wrong here
Improper seating is possible, but given that the original modules work and the new ones all fail, a systematic issue like rank mismatch is more likely.
Common exam traps
Common exam trap: NAT rules depend on direction and matching traffic
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.
Trap categories for this question
Scenario analysis trap
The scenario states the new modules are registered ECC, so this is not the issue.
Detailed technical explanation
How to think about this question
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.
KKey Concepts to Remember
- Static NAT maps one inside address to one outside address.
- PAT allows many inside hosts to share one public address using ports.
- Inside local and inside global describe the private and translated addresses.
- NAT ACLs identify traffic for translation, not always security filtering.
TExam Day Tips
- Identify inside and outside interfaces first.
- Check whether the scenario needs static NAT, dynamic NAT or PAT.
- Do not confuse NAT matching ACLs with normal packet-filtering intent.
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
How this comes up in practice
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
Got this wrong? Here's your next step.
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 220-1201 NAT questions on configuration and troubleshooting.
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FAQ
Questions learners often ask
What does this 220-1201 question test?
RAM — This question tests RAM — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The new modules have a different number of ranks (e.g., dual-rank vs. single-rank) than the original modules, causing a rank mismatch that the memory controller cannot handle. — Registered (buffered) ECC memory is designed for servers and has specific compatibility requirements, especially regarding the number of ranks per channel and the memory controller's capabilities. The most likely issue is that the new modules are of a different rank (e.g., dual-rank vs. single-rank) or the server's memory controller cannot handle the total number of ranks when all slots are populated. Mixing ranks or exceeding the rank limit per channel can cause POST failures.
What should I do if I get this 220-1201 question wrong?
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 220-1201 NAT questions on configuration and troubleshooting.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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Last reviewed: Jun 18, 2026
This 220-1201 practice question is part of Courseiva's free CompTIA 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 220-1201 exam.
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