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220-1201 Practice Question: A small office has a single switch connecting all…
A small office has a single switch connecting all workstations. Several users report that they cannot access the internet, but they can still communicate with each other on the local network. What is the most likely cause?
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 router is not properly routing traffic to the internet.
Local communication working while internet access fails points to a problem with the router or the connection between the switch and the router. The switch itself is functioning correctly for local traffic, so the issue is upstream.
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 switch has a bad port.
Why it's wrong here
If a switch port were faulty, only the specific device connected to that port would experience a loss of connectivity. Other users connected to different, working ports on the same switch would retain full local and internet access. The scenario implies that multiple users are affected by the lack of internet access, yet local communication remains functional, which contradicts a single bad switch port being the root cause of the widespread issue.
- ✓
The router is not properly routing traffic to the internet.
Why this is correct
A router's primary function is to forward packets between different networks, specifically between the local area network (LAN) and external networks like the internet (WAN). If the router is misconfigured, powered off, or experiencing a hardware failure, it cannot perform this essential routing function. Consequently, devices on the local network can still communicate with each other via the switch, but any traffic destined for external networks, such as the internet, will be dropped or fail to reach its intended destination.
- ✗
The DNS server is unreachable.
Why it's wrong here
An unreachable DNS server would prevent workstations from resolving human-readable domain names (e.g., google.com) into their corresponding IP addresses. While this would make browsing and accessing resources by name difficult, users could still access internet resources by directly typing their IP addresses into a browser or application, demonstrating that underlying internet connectivity exists. The scenario states "no internet access at all," which implies a more fundamental network layer issue than just name resolution.
- ✗
The workstations have incorrect subnet masks.
Why it's wrong here
An incorrect subnet mask on workstations would misinform them about which IP addresses are considered local versus remote within their network segment. This misconfiguration would severely disrupt local network communication, as devices might attempt to route traffic to the gateway for local destinations, or vice-versa, leading to communication failures even within the LAN. Since the scenario explicitly states that local communication is functional, incorrect subnet masks are not the cause of the internet connectivity failure.
Go deeper
Related to this question
Learn chapter
Network Configuration: IP, DNS, DHCP
Key term
Router
A router is a networking device that connects different networks together and directs data traffic between them by choosing the best path for data to travel.
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
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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.