Computer Science - Networking - Discussion
Discussion Forum : Networking - Section 1 (Q.No. 6)
6.
You have a class A network address 10.0.0.0 with 40 subnets, but are required to add 60 new subnets very soon. You would like to still allow for the largest possible number of host IDs per subnet. Which subnet mask should you assign?
Discussion:
25 comments Page 3 of 3.
Ashis kumar Dash said:
1 decade ago
As we need 100 subnets which is greater than 64 but less than 128 implies portion of IP address identifying no of subnet need at least 7 1's. Therefore subnet mask has at least 15 1's and at most 17 zeros. So max. number of host can be assign to this mask only. So subnet mask will be 255.254.0.0.
Shanky Paul said:
1 decade ago
Agree with Wasimuddin & Sandeep Sanmani.
10.0.0.0 is represented in binary as
0000 1010.0000 0000.0000 0000.0000 0000
Sandeep has explained it clearly.Initially Network address was 10.0.0.0/8 & after creating provision for 100 subnets:
Subnet-0 Network Address= 10.0.0.0/15
Subnet-1 Network Address= 10.1.0.0/15
..
..
..
10.0.0.0 is represented in binary as
0000 1010.0000 0000.0000 0000.0000 0000
Sandeep has explained it clearly.Initially Network address was 10.0.0.0/8 & after creating provision for 100 subnets:
Subnet-0 Network Address= 10.0.0.0/15
Subnet-1 Network Address= 10.1.0.0/15
..
..
..
Sandeep sanmani said:
1 decade ago
We required 100(40+60) subnets.
2^6<100<2^7 OR 64<100<128
no of subnets are 2^7 = 128 (no of 1's are 7)
no of host per subnet are 2^17-2 = 131070 (no of 0's are 17)
11111111.11111110.00000000.00000000
255.254.0.0
2^6<100<2^7 OR 64<100<128
no of subnets are 2^7 = 128 (no of 1's are 7)
no of host per subnet are 2^17-2 = 131070 (no of 0's are 17)
11111111.11111110.00000000.00000000
255.254.0.0
Wasimuddin said:
1 decade ago
Option D is correct since the total number of subnets are 100 which is less the 128 means 7 bits of 2 second octate and 1 bit of second octate is host ID+ 3rd and 4th octat contributing to host ID. SO total number of hosts will be 2 to the power 17.
Kingruke said:
1 decade ago
Option A gives us the most number of host. reason: 255.240.0.0 subnet mask gives 11111111.11110000.00000000.00000000 . The host bits is zero while the subnet bit is 1. 2 to the power 12 equals number of subnet while 2 to the power 20 minus 2 gives us the number of host per subnet.
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