The answer is that the contact’s number has been blocked in the messaging app or phone settings. This is the most likely cause because blocking a specific number only prevents messages from that one sender, while all other SMS traffic continues normally—carrier issues, poor signal, or SIM problems would disrupt all incoming texts, not just a single contact. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your ability to distinguish between global failures and contact-specific settings, a common trap where technicians overlook user-applied blocks. A helpful memory tip: think of it as a “one-contact wall”—if only one sender is silenced, check the block list before blaming the network.
220-1101 Mobile Device Application Support Practice Question
This 220-1201 practice question tests your understanding of mobile device application support. 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 calls stating that their Android phone's messaging app is not receiving SMS messages from one specific contact, but all other contacts work. The phone has good signal strength. 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 contact's number is blocked in the messaging app.
This is a nuanced scenario where a single contact fails. The most likely cause is that the contact's number has been blocked in the messaging app or phone settings, which is a common user mistake. Other causes like carrier issues or SIM problems would affect all messages.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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 phone's SIM card is damaged.
Why it's wrong here
A damaged SIM would affect all SMS functionality, not just messages from one contact.
✓
The contact's number is blocked in the messaging app.
Why this is correct
Blocking a contact prevents their messages from being delivered, while other contacts work normally.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
A corrupted database would likely cause issues with all messages, not just one contact.
✗
The carrier is experiencing an outage in the area.
Why it's wrong here
A carrier outage would affect all SMS traffic, not just a single contact.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A practitioner preparing for the 220-1201 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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 OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 220-1201 OSPF questions on adjacency and route selection.
Mobile Device Application Support — This question tests Mobile Device Application Support — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The contact's number is blocked in the messaging app. — This is a nuanced scenario where a single contact fails. The most likely cause is that the contact's number has been blocked in the messaging app or phone settings, which is a common user mistake. Other causes like carrier issues or SIM problems would affect all messages.
What should I do if I get this 220-1201 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 220-1201 OSPF questions on adjacency and route selection.
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?
OSPF neighbours must agree on key parameters.
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