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FC0-U71 Practice Question: A technician is troubleshooting a network slowdown
A technician is troubleshooting a network slowdown. The technician suspects a loop in the network. Which of the following protocols would prevent such a loop?
⚠ Common exam trap
CompTIA often tests the misconception that protocols like DNS or DHCP can solve layer 2 issues, but the trap here is that candidates confuse network services (DNS, DHCP) with layer 2 loop-prevention mechanisms, forgetting that STP is the only protocol among the options that operates at the data link layer to block redundant paths.
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
✓
STP
STP (Spanning Tree Protocol) is the correct answer because it is specifically designed to prevent network loops in Ethernet networks by dynamically blocking redundant paths. When a loop occurs, broadcast frames can circulate endlessly, causing a broadcast storm that degrades network performance. STP ensures a loop-free topology by placing some switch ports into a blocking state while maintaining redundant links for failover.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
STP
Why this is correct
STP (Spanning Tree Protocol) prevents Layer 2 loops by electing a root bridge and blocking redundant paths, leaving a single active forwarding topology. This directly addresses the suspected switching loop causing the slowdown, since broadcast storms from loops saturate links and CPU.
- ✗
DNS
Why it's wrong here
DNS resolves names to IP addresses and performs no loop prevention at Layer 2. It is tempting because DNS problems can cause apparent slowness, and it would be correct if the question asked which protocol translates hostnames for client connections.
- ✗
NAT
Why it's wrong here
NAT rewrites IP addresses and ports for traffic crossing network boundaries; it does not detect or block Layer 2 loops. It is tempting because NAT is commonly configured on routers, and it would be the right answer if the question asked how private addresses reach the internet.
- ✗
DHCP
Why it's wrong here
DHCP assigns IP addresses and other configuration to hosts; it has no role in detecting or blocking Layer 2 forwarding loops. It is tempting because DHCP is a familiar network service, and it would be the right answer if the question asked which protocol supplies addresses to clients automatically.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This FC0-U71 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 FC0-U71 exam.