valid host address

[leepeiwai]

the answers for the question below is 1,3,4

Can someone help to explain why 2 and 6 not valid host address?

What are three valid host addresses given a subnet mask of 255.255.254.0? (Choose three.)
1.64.100.2.255
2.172.55.33.255
3.64.104.129.0
4.192.168.162.255
5.10.165.55.255
6.128.107.62.0

[Giuseppe Larosa · Accepted solution]

Hello Peiwai,

a valid host address means no broadcast address and no subnet address can be used and means that not all 9 bits of host portion can be all 1 or all 0.

2) 2.172.55.33.255

you need to write in binary the last two octets

  33.255 = 001000||1 1111 1111

as you can see all last 9 bits are set to 1 so this is a broadcast address of subnet 172.55.32.0/23

6) 128.107.62.0

    62.0 in binary  =  0011 111||0  0000 0000

here all last 9 bits are set to zero this is a subnet address 128.107.62.0/23

question five is like 2)

Hope to help

Giuseppe

[leepeiwai]

Thanks, very clearly explained.