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Question 198 of 1,389
Network Infrastructure and ConnectivityhardMultiple ChoiceObjective-mapped

CCNA Network Infrastructure and Connectivity Practice Question

A host is configured with IP address 172.16.100.222/27. Which address is the broadcast address for its subnet?

⚠ Common exam trap

Avoid assuming the broadcast address is always .255 or miscalculating subnet ranges.

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

172.16.100.223

A /27 uses address blocks of 32. In practical terms, the fourth-octet ranges are 0–31, 32–63, 64–95, 96–127, 128–159, 160–191, 192–223, and 224–255. Since 222 falls inside the 192–223 block, the broadcast address is the last address in that block, which is 172.16.100.223. This is a classic subnet-boundary question because it tests whether you can place a host in the correct block and then identify the final address in that block as the broadcast.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • 172.16.100.191

    Why it's wrong here

    The /27 prefix length partitions the address space into 32-address blocks, and 172.16.100.222 falls in the block 172.16.100.192–172.16.100.223. The address 172.16.100.191 is the broadcast address of the preceding block (172.16.100.160–172.16.100.191), so it is outside the current subnet's range and cannot be the broadcast.

    When this WOULD be correct

    In a different question setup where the subnet mask was /26, the subnet would be 172.16.100.128/26, and the broadcast address would be 172.16.100.191. This would make option A the correct answer in that context.

  • 172.16.100.223

    Why this is correct

    The /27 subnet mask indicates 27 network bits, leaving 5 host bits. This creates subnet blocks of 32 addresses. For the host 172.16.100.222, its subnet begins at 172.16.100.192. The broadcast address is the final address in this subnet range, immediately preceding the next network address (172.16.100.224). Therefore, 172.16.100.223 correctly serves as the broadcast address for the subnet defined by the host's /27 configuration.

  • 172.16.100.224

    Why it's wrong here

    172.16.100.224 is the network address of the next /27 subnet, which begins immediately after the current subnet's broadcast at .223. In a /27, the network address is the first address in each 32-address block, so .224 identifies the new block's network ID rather than the broadcast of the block containing .222.

    When this WOULD be correct

    In a different question setup where the subnet mask is /28 (255.255.255.240) and the host IP is 172.16.100.224, the broadcast address would be 172.16.100.239. In this case, option C would be the correct answer.

  • 172.16.100.255

    Why it's wrong here

    172.16.100.255 is the broadcast address for the entire 172.16.100.0/24 network, not for the /27 subnet containing .222. Because the /27 subnet boundary at .224 separates the current block from later ones, the local broadcast stops at .223; .255 belongs to a different, later /27 block.

    When this WOULD be correct

    If the question specified a subnet mask of /24 instead of /27, then 172.16.100.255 would be the broadcast address for the subnet 172.16.100.0/24, making this option correct in that context.

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.

172.16.100.223Correct answer

Why this is correct

The /27 subnet mask indicates 27 network bits, leaving 5 host bits. This creates subnet blocks of 32 addresses. For the host 172.16.100.222, its subnet begins at 172.16.100.192. The broadcast address is the final address in this subnet range, immediately preceding the next network address (172.16.100.224). Therefore, 172.16.100.223 correctly serves as the broadcast address for the subnet defined by the host's /27 configuration.

172.16.100.191Wrong answer — click to see why

Why this is wrong here

172.16.100.191 is the broadcast address of the previous /27 subnet (172.16.100.160/27), not the subnet containing .222. The host .222 is in the 172.16.100.192/27 subnet, so its broadcast is .223.

★ When this WOULD be the correct answer

In a different question setup where the subnet mask was /26, the subnet would be 172.16.100.128/26, and the broadcast address would be 172.16.100.191. This would make option A the correct answer in that context.

Why candidates choose this

Students often miscalculate subnet boundaries or confuse the broadcast of a different subnet. They might think .191 is the broadcast because it is a common broadcast address in a /27 starting at .160.

172.16.100.224Wrong answer — click to see why

Why this is wrong here

172.16.100.224 is the network address of the next /27 subnet (172.16.100.224/27), not a broadcast address. Broadcast addresses are always the last address in a subnet, not the first.

★ When this WOULD be the correct answer

In a different question setup where the subnet mask is /28 (255.255.255.240) and the host IP is 172.16.100.224, the broadcast address would be 172.16.100.239. In this case, option C would be the correct answer.

Why candidates choose this

A student might mistakenly think that .224 is the broadcast because it is the next multiple of 32, but they forget that the broadcast is one less than the next network address.

172.16.100.255Wrong answer — click to see why

Why this is wrong here

172.16.100.255 is the broadcast address of the entire /24 subnet (172.16.100.0/24), not the /27 subnet containing .222. The /27 subnet has a smaller range, so its broadcast is .223.

★ When this WOULD be the correct answer

If the question specified a subnet mask of /24 instead of /27, then 172.16.100.255 would be the broadcast address for the subnet 172.16.100.0/24, making this option correct in that context.

Why candidates choose this

Students often default to the classful broadcast address (ending in .255) without considering the subnet mask. They may assume a /27 still uses the classful broadcast.

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?”

Visual reference

192.168.1.0 /24 256 addresses (254 usable) 192.168.1.0 /25 Subnet A 128 addr (126 usable) 192.168.1.128 /25 Subnet B 128 addr (126 usable) Borrowing 1 bit from host portion creates 2 subnets (/25)

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Last reviewed: May 17, 2026

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