The answer is that the boot mode changed from Legacy to UEFI (or vice versa) after the firmware update. This occurs because a firmware update often resets the UEFI/BIOS settings to factory defaults, including the boot mode configuration. If the hard drive was originally formatted with a Master Boot Record (MBR) for Legacy/CSM booting, but the system now defaults to UEFI mode, the bootloader will not be recognized, triggering the "Boot Device Not Found" error—even though the drive itself is detected in the UEFI settings. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of boot mode compatibility and the impact of firmware resets. A common trap is assuming the drive has failed or that cables are loose, when the real issue is a mismatch between the partition style (MBR vs. GPT) and the boot mode. Remember the memory tip: "Firmware reset? Check the boot mode first—Legacy loves MBR, UEFI needs GPT."
220-1201 BIOS / UEFI Practice Question
This 220-1201 practice question tests your understanding of bios / uefi. 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.
After updating the firmware on a workstation, the system fails to boot and displays a 'Boot Device Not Found' error. The hard drive is detected in UEFI settings. 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 the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The boot mode changed from Legacy to UEFI (or vice versa)
A firmware update can reset UEFI settings to defaults, including boot mode. If the drive was formatted for Legacy (CSM) but the system now defaults to UEFI, or vice versa, the bootloader won't be found. This tests understanding of boot mode compatibility.
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 hard drive has failed due to the update
Why it's wrong here
The drive is still detected in UEFI, so it is likely functional.
✗
Secure Boot is blocking the bootloader
Why it's wrong here
Secure Boot would give a different error and typically only affects non-Windows bootloaders.
✓
The boot mode changed from Legacy to UEFI (or vice versa)
Why this is correct
A firmware update can reset the boot mode, making the existing partition table (MBR vs GPT) incompatible.
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 CMOS battery needs replacement
Why it's wrong here
A dead CMOS battery would lose settings but not cause a boot device error immediately after a firmware update.
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.
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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
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.
BIOS / UEFI — This question tests BIOS / UEFI — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The boot mode changed from Legacy to UEFI (or vice versa) — A firmware update can reset UEFI settings to defaults, including boot mode. If the drive was formatted for Legacy (CSM) but the system now defaults to UEFI, or vice versa, the bootloader won't be found. This tests understanding of boot mode compatibility.
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.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. After replacing a motherboard, a technician installs Windows but the system will not boot from the SSD. The drive is detected in UEFI. The technician recalls the previous motherboard used Legacy BIOS. What is the most likely issue?
medium
A.The SSD is not getting power
✓ B.The UEFI is set to UEFI mode but the drive uses MBR
C.Secure Boot is blocking the Windows bootloader
D.The CMOS battery is dead
Why B: If the new motherboard defaults to UEFI mode but the SSD was formatted with an MBR partition table (for Legacy), the system cannot boot. Changing to Legacy/CSM mode or reinstalling with GPT is needed. This tests understanding of partition table and boot mode compatibility.
Last reviewed: Jun 18, 2026
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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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