Question

Suppose an ISP has the addres like 101.101.128/17.He want to create 4 subnets.What are the prefix (a.b.c.d/x) for this four subnets?

Answer 1

@izanagi.wielder

Answer 2

wait i will have think

Answer 3

i forgot to mention every block mus be the same number of IP address

Answer 4

101.101.101.64/28
101.101.101.80/28
101.101.101.96/28
101.101.101.112/28

Answer 5

how u get it? izanagi

Answer 6

well my bro is a cs learner i asked him

Answer 7

lol,ask for him how to get the result please

Answer 8

you can contact him later
@Ishaan94

Answer 9

ok

Answer 10

thanks

Answer 11

101.101.128.0/19
101.101.160.0/19
101.101.192.0/19
101.101.224.0/19

Answer 12

these are other answers my bro says break it into 4 equal pieces

Answer 13

i do it like this too,but the ans is equal to first form,and i dont know why we use /28 instead /19

Answer 14

to make four subnets i must borrow 2 bits from the host,i think

Answer 15

i am not that deep in it you better contact him

Answer 16

ok thanks izanagi

Answer 17

welcome

Answer 18

You need to convert to binary, each is 8 long in binary so 101.101.128.0/17 converts to:
01100101.01100101.10000000.00000000
The 17 means the 17 first bits will be equal to each adress, this equals to:
01100101.01100101.1 (8+8+1)
Now you have 0000000.00000000 to make 4 equal subnets with, 15 bits
To get 4 different we need to use 2 bits, 00 / 01 / 10 / 11
This will give us the 4 subnets, now with added 2 bits:
01100101.01100101.100 = 101.101.128.0/19
01100101.01100101.101 = 101.101.160.0/19
01100101.01100101.110 = 101.101.192.0/19
01100101.01100101.111 = 101.101.224.0/19

Hope this helps :)

Answer 19

@SigurdS i thougth samething but the answ in book is:
101.101.101.64/28
101.101.101.80/28
101.101.101.96/28
101.101.101.112/28

Answer 20

I think the book is wrong, ask your professor but those are not the same subnets as the one mentioned in the question, as the extra 101 block will not fall into the 128, (01100101 vs 10000000) Books often do silly mistakes like that! (I am not a 100% expert on subnetting so I might be missing something)

Answer 21

thanks