In IPv4 subnet notation, what does '/27' specify in 10.3.3.128/27?

• A. Subnet mask length of 27 bits, yielding 32 addresses
• B. The network ID is 10.3.3.0
• C. The gateway is 10.3.3.1
• D. The broadcast is 10.3.3.31

Answer: (A)

In IPv4, CIDR notation with a slash shows how many bits are fixed for the network portion. A /27 means the first 27 bits form the network, leaving 5 bits for hosts. That yields 2^5 = 32 addresses in each subnet, and the corresponding subnet mask is 255.255.255.224. For 10.3.3.128/27, the subnet spans from 10.3.3.128 to 10.3.3.159 (with 10.3.3.159 as the broadcast address). The network ID is the first address in that block (10.3.3.128), and the gateway would be a usable host within this same block, not a fixed value like 10.3.3.1, which would belong to a different subnet. So the statement describing the mask length and the resulting 32 addresses best captures what /27 specifies.