- A
The new RAM stick is faulty and needs to be replaced.
Why wrong: A faulty stick typically causes a beep code or failure to boot, not a usable memory discrepancy while still being detected in BIOS.
- B
The RAM is not fully seated in the slot.
Why wrong: Improper seating usually results in a no-boot situation or a beep code, not a partial recognition where both sticks are seen but only 8 GB is usable.
- C
The new RAM stick is incompatible with the existing module, causing the system to run in single-channel mode and limiting usable memory.
Mismatched RAM modules (different speeds, timings, or ranks) can force the memory controller to operate in a mode where only one channel is fully utilized, leading to the OS seeing only half the installed capacity.
- D
The motherboard only supports up to 8 GB of RAM.
Why wrong: If the motherboard had a 8 GB limit, the BIOS would not detect 16 GB. The fact that the BIOS sees both sticks indicates the motherboard supports the capacity.
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 customer reports that their desktop PC, which originally had 8 GB of RAM, is now very slow after they installed a second 8 GB stick. The system boots and shows 16 GB in the BIOS, but the OS only reports 8 GB usable. What is the most likely cause?
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 RAM stick is incompatible with the existing module, causing the system to run in single-channel mode and limiting usable memory.
This scenario describes a common issue where mismatched memory modules cause the system to operate in single-channel mode or fail to address all installed RAM. The most likely cause is that the new RAM stick is not compatible with the existing module, often due to differences in speed, timings, or rank, forcing the system to run at the lower common denominator or disabling dual-channel support. The BIOS sees both sticks, but the OS may only report the usable memory from one channel if the modules are mismatched.
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 stick is faulty and needs to be replaced.
Why it's wrong here
A faulty stick typically causes a beep code or failure to boot, not a usable memory discrepancy while still being detected in BIOS.
- ✗
The RAM is not fully seated in the slot.
Why it's wrong here
Improper seating usually results in a no-boot situation or a beep code, not a partial recognition where both sticks are seen but only 8 GB is usable.
- ✓
The new RAM stick is incompatible with the existing module, causing the system to run in single-channel mode and limiting usable memory.
Why this is correct
Mismatched RAM modules (different speeds, timings, or ranks) can force the memory controller to operate in a mode where only one channel is fully utilized, leading to the OS seeing only half the installed capacity.
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 motherboard only supports up to 8 GB of RAM.
Why it's wrong here
If the motherboard had a 8 GB limit, the BIOS would not detect 16 GB. The fact that the BIOS sees both sticks indicates the motherboard supports the capacity.
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
Improper seating usually results in a no-boot situation or a beep code, not a partial recognition where both sticks are seen but only 8 GB is usable.
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 RAM stick is incompatible with the existing module, causing the system to run in single-channel mode and limiting usable memory. — This scenario describes a common issue where mismatched memory modules cause the system to operate in single-channel mode or fail to address all installed RAM. The most likely cause is that the new RAM stick is not compatible with the existing module, often due to differences in speed, timings, or rank, forcing the system to run at the lower common denominator or disabling dual-channel support. The BIOS sees both sticks, but the OS may only report the usable memory from one channel if the modules are mismatched.
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
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