The answer is to test the DC jack for continuity. Since the AC adapter voltage is confirmed at 19V, the power supply itself is functional, meaning the fault lies within the laptop’s internal power delivery path. The DC jack is a common failure point on laptops due to mechanical stress from repeated plugging and unplugging, which can crack solder joints or break internal wiring, preventing voltage from reaching the motherboard even when the adapter is seated. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your ability to isolate power issues systematically; a common trap is assuming the adapter is bad when voltage is present, but the real clue is the charging LED not illuminating. Remember the mnemonic “Voltage Verified, Jack Justified” — if the adapter outputs correct voltage but the laptop won’t charge, always suspect the DC jack first.
220-1101 Mobile Devices Troubleshooting Practice Question
This 220-1201 practice question tests your understanding of mobile devices troubleshooting. 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 brings in a laptop that will not charge. The technician checks the AC adapter with a multimeter and gets 19V output. When the adapter is plugged into the laptop, the charging LED does not illuminate. What should the technician check next?
Why wrong: A faulty battery might not hold a charge, but it would not prevent the charging LED from lighting when the adapter is plugged in.
B
Test the DC jack for continuity
A broken DC jack or loose connection can interrupt power delivery even if the adapter is good. Checking continuity verifies the path from jack to motherboard.
C
Update the laptop's BIOS
Why wrong: A BIOS update is unlikely to resolve a hardware power delivery issue, especially when the adapter is known to output voltage.
D
Replace the AC adapter with a universal one
Why wrong: Since the original adapter outputs correct voltage, replacing it is unnecessary and would not fix a broken DC jack.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Test the DC jack for continuity
Since the AC adapter is outputting correct voltage, the issue is likely in the power delivery path. The DC jack is a common failure point due to mechanical stress or broken solder joints. Testing continuity at the jack is a logical next step.
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.
✗
Replace the laptop's battery
Why it's wrong here
A faulty battery might not hold a charge, but it would not prevent the charging LED from lighting when the adapter is plugged in.
✓
Test the DC jack for continuity
Why this is correct
A broken DC jack or loose connection can interrupt power delivery even if the adapter is good. Checking continuity verifies the path from jack to motherboard.
Related concept
Static NAT maps one inside address to one outside address.
✗
Update the laptop's BIOS
Why it's wrong here
A BIOS update is unlikely to resolve a hardware power delivery issue, especially when the adapter is known to output voltage.
✗
Replace the AC adapter with a universal one
Why it's wrong here
Since the original adapter outputs correct voltage, replacing it is unnecessary and would not fix a broken DC jack.
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
Command / output trap
A BIOS update is unlikely to resolve a hardware power delivery issue, especially when the adapter is known to output voltage.
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.
Mobile Devices Troubleshooting — This question tests Mobile Devices Troubleshooting — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: Test the DC jack for continuity — Since the AC adapter is outputting correct voltage, the issue is likely in the power delivery path. The DC jack is a common failure point due to mechanical stress or broken solder joints. Testing continuity at the jack is a logical next step.
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.
What is the key concept behind this question?
Static NAT maps one inside address to one outside address.
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