- A
The DHCP server is leasing IP addresses with a short lease time.
Why wrong: Short lease times cause renewal traffic but not jitter or packet loss.
- B
The DNS server is responding slowly to queries.
Why wrong: Slow DNS might delay call setup but doesn't cause jitter or packet loss during a call.
- C
The SIP server is overloaded with registration requests.
Why wrong: SIP server overload can cause registration failures but not jitter or packet loss on established calls.
- D
The network is not prioritizing VoIP traffic via QoS.
Without QoS, real-time traffic like VoIP competes with other data, causing jitter and packet loss.
Question 622 of 1,020
VoIP Call Quality: QoS Prioritization
This 220-1201 practice question tests your understanding of network services. 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 company uses a cloud-based VoIP service, and users report intermittent call drops and poor audio quality. Network monitoring shows high jitter and packet loss. Which service is most likely contributing to the problem?
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.
Quick Answer
The answer is that the network is not prioritizing VoIP traffic via QoS. When jitter and packet loss are present alongside intermittent call drops, the root cause is almost always a failure to configure Quality of Service, which ensures real-time voice packets are given priority over less time-sensitive data like web browsing or file downloads. On the CompTIA A+ Core 1 220-1201 exam, this scenario tests your understanding of how network services impact real-time applications; a common trap is to blame SIP, DHCP, or DNS, but those protocols handle signaling or addressing, not traffic prioritization. Remember that SIP sets up the call, but QoS keeps the call clear—a useful mnemonic is “SIP starts it, QoS smooths it.”
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 network is not prioritizing VoIP traffic via QoS.
High jitter and packet loss directly degrade real-time VoIP traffic, causing call drops and poor audio. QoS (Quality of Service) mechanisms like DiffServ or 802.1p prioritize voice packets over other traffic, ensuring low latency and consistent delivery. Without QoS, the network treats VoIP packets the same as bulk data, leading to the reported symptoms.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 DHCP server is leasing IP addresses with a short lease time.
Why it's wrong here
Short lease times cause renewal traffic but not jitter or packet loss.
- ✗
The DNS server is responding slowly to queries.
Why it's wrong here
Slow DNS might delay call setup but doesn't cause jitter or packet loss during a call.
- ✗
The SIP server is overloaded with registration requests.
Why it's wrong here
SIP server overload can cause registration failures but not jitter or packet loss on established calls.
- ✓
The network is not prioritizing VoIP traffic via QoS.
Why this is correct
Without QoS, real-time traffic like VoIP competes with other data, causing jitter and packet loss.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Note the distinction between application-layer issues (SIP overload, DNS) and transport/network-layer issues (jitter, loss). Candidates often mistakenly attribute packet-level symptoms to server overload rather than missing QoS.
Detailed technical explanation
How to think about this question
VoIP traffic is extremely sensitive to delay variation (jitter) and packet loss; even 1% loss can cause audible artifacts. QoS typically uses DSCP EF (46) for voice RTP packets and strict priority queuing to ensure they are forwarded before other traffic. In a cloud-based VoIP scenario, the LAN edge router must trust or re-mark DSCP values and apply shaping/policing to prevent congestion drops.
KKey Concepts to Remember
- Read the scenario before looking for a memorised answer.
- Find the constraint that changes the correct option.
- Eliminate answers that are true in general but not in this case.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
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FAQ
Questions learners often ask
What does this 220-1201 question test?
Network Services — This question tests Network Services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: The network is not prioritizing VoIP traffic via QoS. — High jitter and packet loss directly degrade real-time VoIP traffic, causing call drops and poor audio. QoS (Quality of Service) mechanisms like DiffServ or 802.1p prioritize voice packets over other traffic, ensuring low latency and consistent delivery. Without QoS, the network treats VoIP packets the same as bulk data, leading to the reported symptoms.
What should I do if I get this 220-1201 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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?
Read the scenario before looking for a memorised answer.
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 →
Same concept, more angles
1 more ways this is tested on 220-1201
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. A customer complains that their VoIP phone intermittently drops calls. A technician checks the network and finds high latency and jitter during peak hours. Which network service should be configured to prioritize VoIP traffic?
medium- A.DHCP
- ✓ B.QoS
- C.DNS
- D.VPN
Why B: B is correct because Quality of Service (QoS) is the network service designed to manage bandwidth and prioritize time-sensitive traffic like VoIP. By marking VoIP packets (e.g., with DSCP EF or CoS 5) and applying queuing mechanisms such as LLQ or CBWFQ, QoS reduces latency and jitter during congestion, directly addressing the intermittent call drops during peak hours.
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Last reviewed: Jul 4, 2026
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