CCNA Network Infrastructure and Connectivity Practice Question
A host address is 10.55.8.117/29. Which address is the network address of the subnet?
⚠ Common exam trap
Be careful not to confuse the network address with the first usable host or the broadcast address.
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
✓
10.55.8.112
A /29 subnet has a block size of 8. In practical terms, the relevant last-octet blocks are 112-119 for this host. That means the network address is 10.55.8.112. Once you identify the correct block, the first address in the block is the network address. This is a useful addressing-boundary question because it checks careful block calculation, not memorized guesses.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
10.55.8.112
Why this is correct
10.55.8.112 is the network address because the /29 prefix length equates to a 255.255.248 subnet mask, creating subnets with 8 addresses each. The host address 10.55.8.117 falls within the range 112 through 119, so the network address is the first address in that block, 10.55.8.112, with 10.55.8.119 as the broadcast address.
- ✗
10.55.8.119
Why it's wrong here
10.55.8.119 is not the network address; it is the directed broadcast address for the /29 subnet that contains 10.55.8.117. In a /29 subnet, the last address in the block (112-119) is reserved for broadcast traffic and cannot be assigned to a host or used as the network identifier. The network address is always the first address, 10.55.8.112.
When this WOULD be correct
In a different question where the subnet mask is /29 and the host address is 10.55.8.119, asking for the broadcast address of the subnet, option B would be correct as it represents the last usable address before the broadcast address of 10.55.8.127.
- ✗
10.55.8.120
Why it's wrong here
10.55.8.120 is incorrect because it is the network address of the next /29 subnet, not the one containing 10.55.8.117. With a block size of 8, the subnet boundaries are at multiples of 8: 112, 120, 128, and so on. Since 117 is between 112 and 119, the correct network is 10.55.8.112, while 10.55.8.120 begins the subsequent subnet.
When this WOULD be correct
If the question were to ask for the broadcast address of the subnet instead of the network address, 10.55.8.120 could be correct, as it is the last address in the subnet range for 10.55.8.112/29.
- ✗
10.55.8.116
Why it's wrong here
10.55.8.116 is a usable host IP address within the /29 subnet spanning 112-119, but it is not the network address. The network address is the first address of the block, 10.55.8.112, which is reserved to identify the subnet itself. Addresses 113 through 118 are assignable to hosts, making .116 just one of those valid hosts, not the network identifier.
When this WOULD be correct
In a different question setup where the subnet mask is /28 and the host address is 10.55.8.116, option D would be the correct answer as it would then represent the network address for that subnet, which includes addresses from 10.55.8.112 to 10.55.8.127.
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.
✓10.55.8.112Correct answer▾
Why this is correct
10.55.8.112 is the network address because the /29 prefix length equates to a 255.255.248 subnet mask, creating subnets with 8 addresses each. The host address 10.55.8.117 falls within the range 112 through 119, so the network address is the first address in that block, 10.55.8.112, with 10.55.8.119 as the broadcast address.
✗10.55.8.119Wrong answer — click to see why▾
Why this is wrong here
10.55.8.119 is the broadcast address for the subnet 10.55.8.112/29, not the network address. The broadcast address is the last address in the block (112+8-1=119) and is used to send traffic to all hosts in the subnet.
★ When this WOULD be the correct answer
In a different question where the subnet mask is /29 and the host address is 10.55.8.119, asking for the broadcast address of the subnet, option B would be correct as it represents the last usable address before the broadcast address of 10.55.8.127.
Why candidates choose this
Students often confuse the broadcast address with the network address because both are special addresses within the subnet. The broadcast address is the highest address, while the network address is the lowest.
✗10.55.8.120Wrong answer — click to see why▾
Why this is wrong here
10.55.8.120 is the network address of the next /29 subnet (120-127), not the current one. The current subnet ends at 119, so 120 belongs to a different subnet.
★ When this WOULD be the correct answer
If the question were to ask for the broadcast address of the subnet instead of the network address, 10.55.8.120 could be correct, as it is the last address in the subnet range for 10.55.8.112/29.
Why candidates choose this
A common mistake is to assume the network address is the next multiple of 8 after the host address, but the correct network address is the multiple of 8 that is less than or equal to the host address.
✗10.55.8.116Wrong answer — click to see why▾
Why this is wrong here
10.55.8.116 is a valid host address within the subnet 10.55.8.112/29 (usable range: 113-118). It is not the network address, which must be the first address (112).
★ When this WOULD be the correct answer
In a different question setup where the subnet mask is /28 and the host address is 10.55.8.116, option D would be the correct answer as it would then represent the network address for that subnet, which includes addresses from 10.55.8.112 to 10.55.8.127.
Why candidates choose this
Students may think the network address is close to the host address, such as rounding down to the nearest even number, but the correct method is to find the block boundary using the subnet mask.
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
Block size
Block size is the amount of data, measured in bytes, that a system reads or writes in a single operation, affecting storage efficiency and network performance.
Key term
Network address
A network address is a unique identifier that allows devices to find and communicate with each other on a computer network.
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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.