CCNA Network Infrastructure and Connectivity Practice Question

Answer analysis

Option-by-option breakdown

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

• ✓

  172.31.9.193

  Why this is correct

  172.31.9.193 is the first usable host address in the 172.31.9.192/27 subnet. The /27 prefix length yields a 32-address block (256–224 = 32 hosts per subnet), so with a network address of .192, the valid host range begins at .193 and ends at .222 (broadcast .223). Since 172.31.9.200 falls within this subnet, .193 is the lowest usable address in that same range.

• ✗

  172.31.9.192

  Why it's wrong here

  172.31.9.192 is the network address of the /27 subnet that contains the host 172.31.9.200. Since /27 borrows 3 bits, the subnet increments by 32, making .192 the start of the 172.31.9.192–172.31.9.223 block. The network address itself is reserved to identify the subnet and cannot be assigned to a host, so it is not a usable host address.

  When this WOULD be correct

  If the question asked for the subnet address instead of the first usable host, option B would be correct. For example, a question could state, 'What is the subnet address for the network 172.31.9.192/27?'

• ✗

  172.31.9.223

  Why it's wrong here

  172.31.9.223 is the directed broadcast address for the 172.31.9.192/27 subnet. With a /27 mask (255.255.255.224), the block size is 32, so the next network boundary is 172.31.9.224; subtracting 1 gives .223 as the broadcast address. This address is not usable as a host because broadcasts cannot be assigned to interfaces, so it cannot be the first usable host.

  When this WOULD be correct

  If the question were to ask for the last usable host address in the subnet 172.31.9.192/27, then option C, 172.31.9.223, would be the correct answer, as it is the highest usable address before the broadcast address.

• ✗

  172.31.9.201

  Why it's wrong here

  172.31.9.201 is a valid host address within the 172.31.9.192/27 subnet, but it is not the first usable host. Because the network address is 172.31.9.192, the first usable IPv4 address is always one greater, so .193 is the correct first host. The .201 address is simply a later assignable host in the range .193 through .222, so it fails to satisfy the 'first usable' condition.

  When this WOULD be correct

  In a different question that asks for the second usable host in the subnet 172.31.9.192/27, option D would be correct, as it would be the second usable address after 172.31.9.193.

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.

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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