220-1101 Hardware and Network Troubleshooting Practice Question
A technician is troubleshooting a user's wired desktop that intermittently loses network connectivity for short periods (1-2 minutes) several times a day. During the outage, the link light on the NIC remains lit and continuous. The technician has already replaced the Ethernet cable and the NIC. The switch port is configured for auto-negotiation. Which of the following should the technician check NEXT?
⚠ Common exam trap
Test-takers frequently assume a lit link light means the physical layer is fully functional, but a duplex mismatch is a Layer 2 issue that still allows the link light to remain on while causing intermittent connectivity.
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
✓
Check the network driver settings for duplex mismatch.
The symptoms—intermittent connectivity with the link light remaining lit—strongly suggest a duplex mismatch. When one side is set to full duplex and the other to half duplex (or auto-negotiation fails), the half-duplex side detects collisions and triggers retransmissions, causing 1–2 minute outages. Since the cable and NIC have been replaced, the next logical step is to check the NIC driver settings for a forced duplex or speed setting that conflicts with the switch port's auto-negotiation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Verify the switch port is configured for the correct VLAN.
Why it's wrong here
Incorrect VLAN assignment on a switch port causes immediate and persistent layer-2 isolation: the host is placed in the wrong broadcast domain, so it cannot communicate with devices in its expected subnets and typically loses all access to the corporate network or the internet. The user's symptom is intermittent, short-lived loss while general connectivity remains possible, which is the opposite of what a VLAN error would produce. While verifying the switch port configuration might be part of a broader network check, it is not the primary action for an intermittent wired desktop issue; physical-layer and duplex settings should be examined first.
When this WOULD be correct
A technician is troubleshooting a desktop that cannot connect to any network resources, but other devices on the same switch work. The switch port is configured for a specific VLAN, and the desktop's IP configuration is correct. In this scenario, verifying the VLAN assignment would be the next step.
- ✓
Check the network driver settings for duplex mismatch.
Why this is correct
A duplex mismatch occurs when one device operates at full duplex and the other at half duplex. This can cause intermittent connectivity, high error rates, and performance degradation while the link remains up. Checking and forcing the correct duplex setting (or leaving both sides on auto) often resolves the issue.
- ✗
Check the DNS server configuration on the computer.
Why it's wrong here
DNS is only consulted during name resolution; once a connection is established, the operating system caches and uses the resolved IP address, so DNS servers are not involved in the actual data path. If the user can still reach resources by IP address or an existing session keeps dropping, the outage is not caused by DNS. Intermittent connectivity typically points to layer-1/2 issues such as faulty cabling, a failing NIC, or a duplex mismatch, so checking DNS configuration would not explain the transient loss of connectivity.
When this WOULD be correct
A user reports that they can access websites by IP address but not by domain name, and other users on the same network have no issues. The technician should check the DNS server configuration on the computer.
- ✗
Disable the firewall to rule out a security issue.
Why it's wrong here
Disabling the firewall is not an appropriate diagnostic step because a host firewall applies access rules deterministically: if it were blocking traffic, the user would see consistent, predictable failures for the affected protocol or destination, not short random dropouts. A duplex mismatch operates at the physical/data-link layer, causing frame corruption and late collisions even though the link stays up, which a firewall cannot influence. Furthermore, disabling the firewall exposes the system to additional risk without yielding any useful information about the intermittent connectivity.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 220-1101 exam frequently reuses these exact scenarios with slightly different constraints.
✓Check the network driver settings for duplex mismatch.Correct answer▾
Why this is correct
A duplex mismatch occurs when one device operates at full duplex and the other at half duplex. This can cause intermittent connectivity, high error rates, and performance degradation while the link remains up. Checking and forcing the correct duplex setting (or leaving both sides on auto) often resolves the issue.
✗Verify the switch port is configured for the correct VLAN.Wrong answer — click to see why▾
Why this is wrong here
The link light remains lit during outages, indicating Layer 1 connectivity is intact. Intermittent short outages with auto-negotiation suggest a duplex mismatch, not VLAN misconfiguration, which would typically cause persistent connectivity issues or complete loss.
★ When this WOULD be the correct answer
A technician is troubleshooting a desktop that cannot connect to any network resources, but other devices on the same switch work. The switch port is configured for a specific VLAN, and the desktop's IP configuration is correct. In this scenario, verifying the VLAN assignment would be the next step.
Why candidates choose this
Candidates may confuse intermittent connectivity with VLAN issues, thinking that incorrect VLAN tagging could cause periodic drops, but VLAN problems usually result in consistent failure to communicate with devices outside the VLAN.
✗Check the DNS server configuration on the computer.Wrong answer — click to see why▾
Why this is wrong here
The symptom is intermittent connectivity with link light on, indicating a layer 1/2 issue. DNS server configuration would cause name resolution failures, not brief complete outages with link light active.
★ When this WOULD be the correct answer
A user reports that they can access websites by IP address but not by domain name, and other users on the same network have no issues. The technician should check the DNS server configuration on the computer.
Why candidates choose this
Candidates often associate network connectivity problems with DNS misconfiguration, but DNS issues typically affect name resolution, not intermittent connectivity with link light on.
Analysis generated from the official 220-1101blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 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 220-1101 exam.