mediumMultiple Choice
220-1201 Practice Question: A customer complains that their VoIP phone…
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?
⚠ Common exam trap
Many exam-takers confuse network services like DHCP (address assignment) and DNS (name resolution) with traffic management. QoS is the correct service to prioritize VoIP traffic and reduce latency/jitter during congestion.
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
✓
QoS
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.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
DHCP
Why it's wrong here
DHCP assigns IP addresses and lease options; it cannot classify or queue packets, so jitter and latency during peak hours persist. It is tempting because DHCP scope options can deliver VoIP parameters such as TFTP server addresses, but that is provisioning, not traffic prioritisation, which requires QoS marking and queuing.
- ✓
QoS
Why this is correct
QoS classifies and marks VoIP packets, then schedules them through low-latency priority queues, so voice frames bypass the queuing delay causing jitter and call drops during peak congestion. This directly addresses the latency and jitter the technician observed.
- ✗
DNS
Why it's wrong here
DNS resolves hostnames to IP addresses; it neither inspects nor marks RTP packets, so peak-hour jitter and latency remain unaddressed. It is tempting because VoIP endpoints rely on DNS for SIP server discovery, making it a correct choice when call setup fails through name resolution errors rather than congestion.
- ✗
VPN
Why it's wrong here
A VPN encrypts and tunnels traffic between endpoints; it adds encapsulation overhead and does not classify or queue RTP above other flows, so jitter worsens. It is tempting because VPNs suit securing remote VoIP calls over untrusted networks, but here the requirement is prioritising voice on the existing congested LAN.
Go deeper
Related to this question
Learn chapter
Home and SOHO Network Setup
Key term
Quality of Service
Quality of Service (QoS) is a set of technologies used to manage network traffic by prioritizing certain types of data to ensure reliable performance for critical applications.
Key term
Session Initiation Protocol
Session Initiation Protocol (SIP) is a signaling protocol used to start, maintain, and end voice and video calls over IP networks.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.