The answer is a faulty mainboard audio IC (codec). This is correct because the audio IC is the component responsible for routing audio signals to the correct output path—the earpiece during calls versus the loudspeaker for media or speakerphone. When a smartphone earpiece is not working but the loudspeaker works, and the earpiece speaker itself has been tested and confirmed good, the logical failure point is the audio IC or its supporting traces on the mainboard; the loudspeaker’s functionality proves the audio amplification and signal generation are intact, isolating the issue to the switching or routing logic within the codec. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your ability to differentiate between a failed component and a failed connection, with a common trap being to replace the earpiece speaker unnecessarily. A useful memory tip: think of the audio IC as a railroad switch—if the train (audio signal) reaches the loudspeaker track but not the earpiece track, the switch itself is broken.
220-1101 Mobile Device Hardware Servicing Practice Question
This 220-1201 practice question tests your understanding of mobile device hardware servicing. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 technician is servicing a smartphone with a non-functional earpiece speaker during calls, but the loudspeaker works fine. After testing, the earpiece speaker itself is determined to be good. Which component is most likely faulty?
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 mainboard audio IC (codec).
This question tests understanding of audio routing in mobile devices. The audio IC or codec manages which speaker is used. If the earpiece speaker is good but doesn't work, the audio IC may be damaged, or the connection traces are broken. The loudspeaker working suggests the audio path for that output is intact.
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 charging port flex cable.
Why it's wrong here
The charging port flex typically handles power and data, not audio routing.
✓
The mainboard audio IC (codec).
Why this is correct
The audio IC controls which speaker receives sound; a fault here can disable the earpiece while leaving the loudspeaker functional.
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 SIM card slot.
Why it's wrong here
SIM slot only handles network identification, not audio.
✗
The battery connector.
Why it's wrong here
Battery connector issues would cause power problems, not selective audio failure.
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.
Mobile Device Hardware Servicing — This question tests Mobile Device Hardware Servicing — Static NAT maps one inside address to one outside address..
What is the correct answer to this question?
The correct answer is: The mainboard audio IC (codec). — This question tests understanding of audio routing in mobile devices. The audio IC or codec manages which speaker is used. If the earpiece speaker is good but doesn't work, the audio IC may be damaged, or the connection traces are broken. The loudspeaker working suggests the audio path for that output is intact.
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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