The answer is that the octet value 300 exceeds the maximum of 255, making the IP address 192.168.1.300 invalid. IPv4 addresses are 32-bit numbers divided into four octets, each ranging from 0 to 255, because each octet represents 8 bits, and 2^8 minus 1 equals 255. Since 300 is greater than this upper bound, the address cannot exist in standard IPv4 addressing. On the CompTIA A+ Core 1 220-1201 exam, this concept tests your understanding of IP address structure and subnetting fundamentals, often appearing as a trap where a seemingly plausible address like 192.168.1.300 is used to see if you recall the octet range. A common memory tip is to remember that IP octets are like a 0–255 scale, similar to RGB color values, so any number above 255 is automatically invalid.
220-1101 Network Configuration Concepts Practice Question
This 220-1201 practice question tests your understanding of network configuration concepts. 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 company's network uses a /24 subnet mask. The IT manager asks a technician to configure a new server with a static IP address of 192.168.1.300. The technician knows this is invalid. What is the reason this IP address cannot be used?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The octet value 300 exceeds the maximum of 255.
IPv4 addresses are 32-bit numbers, and each octet ranges from 0 to 255. The value 300 exceeds the maximum of 255, making the address invalid. This is a fundamental concept in IP addressing.
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 address is outside the private IP range.
Why it's wrong here
192.168.1.x is within the private range (192.168.0.0/16), but the octet value 300 is the problem, not the range.
✗
The address is a broadcast address.
Why it's wrong here
The broadcast address for 192.168.1.0/24 is 192.168.1.255, not 192.168.1.300.
✗
The address is a network address.
Why it's wrong here
The network address is 192.168.1.0, and 192.168.1.300 is not a valid address at all.
✓
The octet value 300 exceeds the maximum of 255.
Why this is correct
Each octet in an IPv4 address must be between 0 and 255. 300 is invalid, so the address cannot be used.
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.
Network Configuration Concepts — This question tests Network Configuration Concepts — CIDR notation defines the prefix length..
What is the correct answer to this question?
The correct answer is: The octet value 300 exceeds the maximum of 255. — IPv4 addresses are 32-bit numbers, and each octet ranges from 0 to 255. The value 300 exceeds the maximum of 255, making the address invalid. This is a fundamental concept in IP addressing.
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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