DNS Misconfiguration Causes Internet Access Failure Despite Working Ping
A technician is setting up a small office network. The router is configured with DHCP and provides addresses in the 192.168.1.0/24 range. A workstation obtains an IP address of 192.168.1.15 but cannot access any external websites. The workstation can ping the default gateway (192.168.1.1) and other local workstations. Which of the following is the most likely cause?
⚠ Common exam trap
The 220-1101 exam often tests the distinction between Layer 3 connectivity (ping to gateway) and application-layer functionality (DNS resolution), trapping candidates who assume that successful gateway pings guarantee full internet access.
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 DNS server address is not configured
The workstation can ping the default gateway and local devices, confirming that Layer 3 connectivity and the default gateway are functional. However, it cannot access external websites, which typically requires DNS resolution to translate domain names to IP addresses. Since the router's DHCP is configured but the workstation lacks a DNS server address, name resolution fails, preventing web access while IP-level communication remains intact.
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 workstation's subnet mask is incorrect
Why it's wrong here
An incorrect subnet mask—such as using 255.255.0.0 instead of 255.255.255.0—would place the default gateway (192.168.1.1) outside the workstation's local subnet. This would force the client to attempt routing through a gateway it cannot directly reach, breaking ARP resolution and preventing any successful ping to 192.168.1.1. Since the workstation can ping the gateway, the subnet mask must be consistent with the /24 network, so this option is not the cause of the name-resolution failure.
- ✗
The default gateway is not set
Why it's wrong here
If the default gateway were not set, the workstation would have no route to reach any IP address outside its own subnet, causing 'Destination Host Unreachable' errors for remote traffic. However, the workstation successfully pings 192.168.1.1, which is the gateway, indicating it is configured and reachable at the local link level. Even if the gateway were missing, that would not directly interfere with the DNS resolver; it would only prevent reaching the DNS server, but here the resolver has no server address to query at all, making this explanation incorrect.
- ✓
The DNS server address is not configured
Why this is correct
The workstation has obtained a valid statically or DHCP-assigned IP address (192.168.1.15) and can ping the router at 192.168.1.1, proving Layer 3 connectivity is functioning. When the user attempts to access a website by domain name, the system's resolver has no DNS server IP address to send the query to, so name resolution fails even though IP communication works. This symptom—network connectivity is fine but hostnames do not resolve—classically points to a missing or misconfigured DNS server option (option 6) in the DHCP lease or an empty static-DNS field on the client.
- ✗
The router's DHCP pool is exhausted
Why it's wrong here
A DHCP pool that is exhausted would prevent the router from leasing any new addresses, causing connected clients to fall back to an Automatic Private IP Addressing (APIPA) address in the 169.254.0.0/16 range or to have no IP configuration at all. Since the workstation already holds a valid lease (192.168.1.15) from the router's DHCP pool, the pool is demonstrably not exhausted. Furthermore, an exhausted pool would manifest as an IP-layer problem, not a DNS resolution problem, so this option cannot explain the observed symptom of failing to resolve domain names.
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JA
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.