A network administrator needs to divide a Class B network into four equal subnets, each with a host range of 1,000 hosts. Which of the following subnet masks should the administrator use?
The best answer is B. 255.255.252.0 , which is a /22 mask. A Class B network starts with a default mask of 255.255.0.0 or /16 . The question says the administrator wants four equal subnets , which means borrowing 2 bits from the host portion, since 2 borrowed bits gives 2² = 4 subnets . That moves the mask from /16 to /18 if subnetting is based only on splitting the Class B into four equal parts.
However, the answer choices point toward the host requirement as the deciding factor. Each subnet needs to support about 1,000 hosts . A /22 leaves 10 host bits , which gives 2¹⁰ = 1024 total addresses , or 1022 usable hosts after subtracting the network and broadcast addresses. That fits the requirement. Among the options provided, 255.255.252.0 is the only mask that supports around 1,000 hosts per subnet.
The smaller masks, /24 and /25 , do not allow enough hosts. The default Class B mask, /16 , does not subnet the network at all. Based on the available choices and the host-capacity requirement, 255.255.252.0 is the correct exam answer.
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