hardMultiple ChoiceObjective-mapped
220-1201 Practice Question: A technician is troubleshooting a network where…
A technician is troubleshooting a network where users intermittently lose connectivity to a critical database server. The technician notices that the server's IP address is being duplicated on the network. Which protocol is responsible for detecting and reporting this conflict?
⚠ Common exam trap
Many candidates mistakenly think DHCP handles conflict detection, but DHCP only avoids conflicts during assignment—it does not monitor for conflicts after the lease is granted, which is why ARP is the correct answer.
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
✓
ARP
The Address Resolution Protocol (ARP) is responsible for detecting and reporting IP address conflicts. When a device sends an ARP probe or gratuitous ARP, it announces its IP address; if another device responds, a conflict is detected. This mechanism allows the operating system to alert the user or log the error, as seen in Windows with the 'IP address conflict' notification.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
ARP
Why this is correct
ARP (Address Resolution Protocol) is the correct answer because it directly operates at Layer 2 to map IP addresses to MAC addresses on a local network segment. When an IP address conflict occurs, multiple devices may respond to ARP requests for the same IP, causing network devices' ARP caches to become unstable and frequently update with conflicting MAC addresses. Many operating systems actively use ARP probes or gratuitous ARP messages upon network interface activation to detect if their assigned IP address is already in use by another device, directly identifying the conflict.
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DHCP
Why it's wrong here
DHCP (Dynamic Host Configuration Protocol) is incorrect because its primary function is to assign IP addresses and other network configuration parameters to clients, not to directly detect IP conflicts. While a DHCP server can be configured to perform conflict detection (e.g., by sending an ICMP ping or an ARP probe to a proposed IP address before offering it), DHCP itself is not the protocol that performs the detection. It relies on other network protocols to verify address availability, making it an indirect mechanism rather not the direct detection protocol.
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ICMP
Why it's wrong here
ICMP (Internet Control Message Protocol) is incorrect because it is primarily used for error reporting and network diagnostics, such as the `ping` utility, which tests connectivity between hosts. While a device could theoretically ping its own assigned IP address to see if another device responds, this is not a standard or reliable method for detecting an IP conflict. ICMP does not directly reveal the MAC address of a conflicting device, nor does it inherently manage the mapping of IP to MAC addresses required for direct conflict identification.
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DNS
Why it's wrong here
DNS (Domain Name System) is incorrect because its fundamental role is to translate human-readable hostnames into numerical IP addresses, and vice-versa. DNS operates at the application layer and is entirely unrelated to the detection of duplicate IP addresses on a local network segment. It has no inherent mechanism to monitor for IP address conflicts or to report when two different devices are configured with the same IP address, as its database is for name resolution, not real-time network address management.
Go deeper
Related to this question
Learn chapter
Mobile Device Types and Features
Key term
ARP
Address Resolution Protocol (ARP) is a network protocol used to map a device's IP address to its physical MAC address so data can be delivered correctly on a local network.
Key term
IP address
An IP address is a unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication.
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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.