The answer is that the default gateway is on a different subnet, which prevents internet access despite successful local pings. This occurs because a device can only communicate directly with hosts on its own subnet; for traffic to reach the internet, the default gateway must share the same network ID as the device’s IP address. In this scenario, the IP 192.168.1.25 with a 255.255.255.0 mask places it on the 192.168.1.0/24 network, while the gateway 192.168.2.1 belongs to 192.168.2.0/24, making it unreachable without a router between them. On the CompTIA A+ Core 1 220-1201 exam, this concept tests your understanding of IP addressing and routing fundamentals, often appearing as a common trap where the gateway is misconfigured with a different third octet. A reliable memory tip is “gateway must be on your own block”—if the subnet mask is 255.255.255.0, the first three octets of the IP and gateway must match for local reachability.
220-1101 IP Addressing Practice Question
This 220-1201 practice question tests your understanding of ip addressing. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A user reports that they cannot access the internet, but they can ping other devices on the local network. The technician checks the IP configuration and sees: IP: 192.168.1.25, Subnet Mask: 255.255.255.0, Default Gateway: 192.168.2.1. What is the issue?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The default gateway is on a different subnet.
The default gateway must be on the same subnet as the device's IP. Here, the IP is on 192.168.1.0/24, but the gateway is on 192.168.2.0/24, so traffic cannot be routed out. This tests the concept that the gateway must be reachable locally.
Key principle: Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
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 subnet mask is incorrect.
Why it's wrong here
The subnet mask 255.255.255.0 is correct for a /24 network and matches the IP.
✓
The default gateway is on a different subnet.
Why this is correct
The gateway 192.168.2.1 is on a different subnet than the device's IP 192.168.1.25, so the device cannot send packets to it.
192.168.1.25 is a valid host address, not the broadcast address (which would be 192.168.1.255).
✗
The DNS server is misconfigured.
Why it's wrong here
DNS issues would affect name resolution, but the inability to ping the gateway indicates a routing problem, not DNS.
Common exam traps
Common exam trap: usable hosts are not the same as total addresses
Subnetting questions often tempt you into counting all addresses. In normal IPv4 subnets, the network and broadcast addresses are not usable host addresses.
Detailed technical explanation
How to think about this question
Subnetting questions test whether you can identify the network, broadcast address, usable range, mask and correct subnet. Slow down enough to calculate the block size correctly.
KKey Concepts to Remember
CIDR notation defines the prefix length.
Block size helps identify subnet boundaries.
Network and broadcast addresses are not usable hosts in normal IPv4 subnets.
The required host count determines the smallest suitable subnet.
TExam Day Tips
→Write the block size before choosing the subnet.
→Check whether the question asks for hosts, subnets or a specific address range.
→Do not confuse /24, /25, /26 and /27 host counts.
Key takeaway
Count usable hosts — not total addresses — and remember that the network and broadcast addresses are not available to hosts in standard IPv4 subnets.
Real-world example
How this comes up in practice
A network engineer segments a warehouse floor into three subnets: 20 scanners, 5 printers, and 2 management hosts. Picking the wrong mask wastes addresses or leaves too few usable hosts. Exam questions test whether you can apply CIDR notation, calculate block size, and identify the correct usable-host range for a given prefix.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 220-1201 question in full detail.
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
IP Addressing — This question tests IP Addressing — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The default gateway is on a different subnet. — The default gateway must be on the same subnet as the device's IP. Here, the IP is on 192.168.1.0/24, but the gateway is on 192.168.2.0/24, so traffic cannot be routed out. This tests the concept that the gateway must be reachable locally.
What should I do if I get this 220-1201 question wrong?
Review block sizes, usable host formulas (2^n − 2), and how to find network and broadcast addresses for /24 through /30. Then practise related 220-1201 subnetting questions on CIDR, address ranges, and subnet selection.
What is the key concept behind this question?
CIDR notation defines the prefix length.
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Question Discussion
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