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谁能给我讲解下这个题目 CCNA的
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Which subnet mask will place all hosts on Network B in the same subnet with the least amount of wasted addresses?
A. 255.255.255.0
B. 255.255.254.0
C. 255.255.252.0
D. 255.255.248.0
Answer: B Explanation:
310 hosts < 512 = 29-> We need a subnet mask of 9 bits 0 -> 1111 1111.1111 1111.1111 1110.0000 0000 -> 255.255.254.0
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楼主 |
发表于 11-8-2017 11:19 PM
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发表于 12-8-2017 04:25 PM
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本帖最后由 (-_-) 于 12-8-2017 04:29 PM 编辑
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发表于 12-8-2017 09:37 PM
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A 的host 是252, 不够
B 的host 是510, 已经多过310
C 的host 是1022
D的host是 2046
所以B的/23刚好 |
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发表于 4-8-2018 11:58 AM
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发表于 24-10-2018 09:39 PM
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A. 255.255.255.0
Host = 2^8 - 2 =254
B. 255.255.254.0
254在host ID(2nd octet)借了七个bit, 剩下1bit(3rd octet) + 8 bits(4th octet)=9, 所以2^9-2 = 508
C. 255.255.252.0
252在host ID(2nd octet)借了六个bit, 剩下2 bits(3rd octet) + 8 bits(4th octet)=10, 所以2^10-2 = 1022
D. 255.255.248.0
248在host ID(2nd octet)借了五个bit, 剩下3 bits(3rd octet) + 8 bits(4th octet)=11, 所以2^11-2 = 2046
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