求解释这题

心魅d

The internetwork is using subnets of the address 192.168.1.0 with a subnet mask of 255.255.255.224. The routingprotocol in use is RIP version 1. Which address could be assigned to the FastEthernet interface on RouterA?
A. 192.168.1.31
B. 192.168.1.64
C. 192.168.1.127
D. 192.168.1.190
E. 192.168.1.192

答案为什么是D??? 求各位帮助解答

byronyj

31, 64, 127, 190, 192中只有190不為{2^5*n}(network address)或{2^5*n-1}(broadcast address)。

心魅d

byronyj 发表于 2018-6-3 13:54
31, 64, 127, 190, 192中只有190不為{2^5*n}(network address)或{2^5*n-1}(broadcast address)。

还是有点不懂呢

心魅d

byronyj 发表于 2018-6-3 13:54
31, 64, 127, 190, 192中只有190不為{2^5*n}(network address)或{2^5*n-1}(broadcast address)。

192.168.1.0 with a subnet mask of 255.255.255.224 <---This is key

192.168.1.0 /27 = 32 (30 host address per subnet (1 Network / 1 Broadcast)

So..

192.168.1.0
192.168.1.32 -
192.168.1.64 - 95
192.168.1.96 - 127
192.168.1.128 - 159
192.168.1.160 - 191 (160 network, 191 Broadcast) last usable is 190.
192.168.1.192

找到比较容易理解的答案了  谢谢anyway

心魅d

byronyj 发表于 2018-6-3 13:54
31, 64, 127, 190, 192中只有190不為{2^5*n}(network address)或{2^5*n-1}(broadcast address)。

192.168.1.0 with a subnet mask of 255.255.255.224 <---This is key

192.168.1.0 /27 = 32 (30 host address per subnet (1 Network / 1 Broadcast)

So..

192.168.1.0
192.168.1.32 -
192.168.1.64 - 95
192.168.1.96 - 127
192.168.1.128 - 159
192.168.1.160 - 191 (160 network, 191 Broadcast) last usable is 190.
192.168.1.192

找到比较容易理解的答案了  谢谢anyway

hh010snake

lanfengjing

Router A下30个主机192.168.1.32/27
Router B下40个主机192.168.1.33/26
Router C下50个主机192.168.1.96/26
以上得出选项ABC都是错的，而E是网络地址，故只能选D。如有不懂请提。

3Q！

lanfengjing

lanfengjing 发表于 2018-6-5 09:46
Router A下30个主机192.168.1.32/27
Router B下40个主机192.168.1.33/26
Router C下50个主机192.168.1.96 ...

Router A下30个主机192.168.1.0/27  上面写错了。3Q！

h19

子网划分

异议熠熠

子网划分后，合理的可分配的主机ip只有 1-31    33-62  97-126 129-158  161-190  193-222
这几段ip地址，所有上面所有的选项只有D选项符合条件

异议熠熠

打错一个，是1-30

异议熠熠

打错一个是1-30

异议熠熠

打错一个是1-30

dxjfflxm

novatipsy