CCNA Network Infrastructure and Connectivity Practice Question
A host uses address 192.168.5.126/25. Which address is the broadcast address for its subnet?
⚠ Common exam trap
Remember that the broadcast address is the last address in the subnet, not the first address of the next subnet or the broadcast for the entire /24.
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
✓
192.168.5.127
A /25 divides the /24 into two halves: 0–127 and 128–255. In plain language, the host address 192.168.5.126 is in the lower half, which runs from .0 through .127. The last address in that block is the broadcast address, so the broadcast is 192.168.5.127. This is a classic subnetting question because it checks whether you can identify the correct block and then select the last address in that block as the broadcast address.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
192.168.5.63
Why it's wrong here
This is wrong because .63 would be the broadcast of a /26 block, not the /25 block containing .126.
When this WOULD be correct
If the question were to ask for the broadcast address of a subnet defined by 192.168.5.0/26, then option A (192.168.5.63) would be correct, as it would represent the broadcast address for that specific subnet range.
- ✓
192.168.5.127
Why this is correct
The /25 CIDR notation specifies a subnet mask of 255.255.255.128, meaning the first 25 bits define the network portion. For the host 192.168.5.126, the network address is 192.168.5.0, as the 25th bit is 0. This subnet, 192.168.5.0/25, encompasses IP addresses from 192.168.5.0 to 192.168.5.127. The broadcast address is always the last address in the subnet range, where all host bits are set to one, which in this scenario is 192.168.5.127.
- ✗
192.168.5.128
Why it's wrong here
This is wrong because .128 is the network address of the upper /25 block.
When this WOULD be correct
If the question specified a subnet mask of /24 instead of /25, then 192.168.5.128 would be the correct broadcast address for the subnet 192.168.5.0/24, which ranges from 192.168.5.0 to 192.168.5.255.
- ✗
192.168.5.255
Why it's wrong here
This is wrong because .255 is the broadcast of the full /24, not the lower /25 block.
When this WOULD be correct
If the question asked for the broadcast address of the 192.168.5.0/24 subnet instead of the /25 subnet, then option D would be correct, as it represents the highest address in that larger subnet.
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 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓192.168.5.127Correct answer▾
Why this is correct
The /25 CIDR notation specifies a subnet mask of 255.255.255.128, meaning the first 25 bits define the network portion. For the host 192.168.5.126, the network address is 192.168.5.0, as the 25th bit is 0. This subnet, 192.168.5.0/25, encompasses IP addresses from 192.168.5.0 to 192.168.5.127. The broadcast address is always the last address in the subnet range, where all host bits are set to one, which in this scenario is 192.168.5.127.
✗192.168.5.63Wrong answer — click to see why▾
Why this is wrong here
Option A (192.168.5.63) is incorrect because it does not fall within the subnet defined by the address 192.168.5.126/25, which has a valid range of 192.168.5.128 to 192.168.5.255 for host addresses.
★ When this WOULD be the correct answer
If the question were to ask for the broadcast address of a subnet defined by 192.168.5.0/26, then option A (192.168.5.63) would be correct, as it would represent the broadcast address for that specific subnet range.
Why candidates choose this
Candidates may be tempted by this option because they might confuse the subnet mask and miscalculate the broadcast address, mistakenly believing that the lower range of addresses is valid for the given subnet.
✗192.168.5.128Wrong answer — click to see why▾
Why this is wrong here
The address 192.168.5.128 is incorrect because it falls outside the subnet defined by 192.168.5.126/25, which includes addresses from 192.168.5.0 to 192.168.5.127. The broadcast address for this subnet is 192.168.5.127.
★ When this WOULD be the correct answer
If the question specified a subnet mask of /24 instead of /25, then 192.168.5.128 would be the correct broadcast address for the subnet 192.168.5.0/24, which ranges from 192.168.5.0 to 192.168.5.255.
Why candidates choose this
Candidates might choose this option due to a misunderstanding of subnetting, mistakenly associating the higher address in the range with the broadcast address without calculating the correct subnet mask.
✗192.168.5.255Wrong answer — click to see why▾
Why this is wrong here
Option D, 192.168.5.255, is incorrect because it is the broadcast address for the entire 192.168.5.0/24 subnet, not the /25 subnet specified in the question.
★ When this WOULD be the correct answer
If the question asked for the broadcast address of the 192.168.5.0/24 subnet instead of the /25 subnet, then option D would be correct, as it represents the highest address in that larger subnet.
Why candidates choose this
Candidates might choose option D due to a misunderstanding of subnetting, confusing the broader /24 range with the specific /25 range, leading them to think of the highest address in the entire subnet.
Analysis generated from the official 200-301blueprint 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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Related to this question
Learn chapter
IPv4 Addressing and Address Classes
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.
Key term
Subnet
A subnet is a logical subdivision of an IP network, created by partitioning a larger network address space using subnet masks.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 practice question is part of Courseiva's free Cisco 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 200-301 exam.