单选题 Your network uses the172.12.0.0 class B address. You need to support 459 hosts per subnet, while accommodating the maximum number of subnets. Which mask would you use?

A、 255.255.0.0.
B、 255.255.128.0.
C、 255.255.224.0.
D、 255.255.254.0.
E、 None of the above

【正确答案】 D

【答案解析】解析：Explanation: To obtain 459 hosts the number of host bits will be 9. This can support a maximum of 510 hosts. To keep 9 bits for hosts means the last bit in the 3rd octet will be 0. This gives 255.255.254.0 as the subnet mask.