Confusing Subnetting Question
sarahanand
Member Posts: 52 ■■□□□□□□□□
in CCNA & CCENT
I found this below scenario on another forum, and expecting a lot of help here in understanding. So I quote
I don't understand the question, Is a subnet being masked again here?
And as for the below, is the range correct?
Wadman's Widgets is a small startup company that has been recently been aquired by Huge Corp. In order to be linked to other areas of Huge Corp, it has been assigned the IP range of 172.20.10.0/23. They have three departments that need to be seperated for security reasons: production, accounting and managment. Production has 100 users, account has 25 and management has 7. In addition, they have a server farm that will need a seperate subnet with 5 IP addresses. In the near future, Huge Corp are looking to double their operation by opening an identical office in the next state and want to account for addressing now.
Your task is to write up a presentation of how you would address this situation. Please explain why you did what you did and feel free to add any graphics, spreadsheets, documents, etc. you would like.
Well, I did my math and knew that each subnet had 510 hosts available, no problem. So I started the math and started issuing my IP blocks as thus:
Production has 100 hosts needing access to the network.
IP Address Pool = 172.20.10.1 - 172.20.11.254
IP Network and Broadcast ID = 172.20.10.0 and 172.20.11.255
Accounting has 24 hosts needing access to the network.
IP Address Pool = 172.20.11.1 - 172.20.12.254
IP Network and Broadcast ID = 172.20.11.0 and 172.20.12.255
Server Hosting has 5 hosts needing access to the network on their own subnet.
IP Address Pool = 172.20.13.1 - 172.20.14.254
IP Network and Broadcast ID = 172.20.13.0 and 172.20.14.255
Management has 7 hosts needing access to the network.
IP Address Pool = 172.20.15.1 - 172.20.16.254
IP Network and Broadcast ID = 172.20.15.0 and 172.20.16.255
Basically copied the same layout on the "identical upcoming expansion" but did so witht he next series of numbers.
While I know that having 510 hosts on a subnet for only 5 or 25 or even 100 hosts alone is not right, the teacher didn't tell us we could move the subnet mask to ensure the proper amount of hosts on the subnet. I don't even know if I am explaining this right... Here is the teacher's analysis (and where I get completely lost and totally frustrated)
Network Needed Given Mask Range 172.20.10.0/24
Production 100 128 /25 172.20.10.0 172.20.10.127
Accounting 25 32 /27 172.20.10.128 172.20.10.159
Management 7 16 /28 172.20.10.160 172.20.10.175
Server Farm 5 8 /29 172.20.10.176 172.20.10.183
172.20.11.0/24
Production 2 100 128 /25 172.20.11.0 172.20.11.127
Accounting 2 25 32 /27 172.20.11.128 172.20.11.159
Management 2 7 16 /28 172.20.11.160 172.20.11.175
Server Farm 2 5 8 /29 172.20.11.176 172.20.11.183
I don't understand the question, Is a subnet being masked again here?
And as for the below, is the range correct?
Production has 100 hosts needing access to the network.
IP Address Pool = 172.20.10.1 - 172.20.11.254
IP Network and Broadcast ID = 172.20.10.0 and 172.20.11.255
Accounting has 24 hosts needing access to the network.
IP Address Pool = 172.20.11.1 - 172.20.12.254 - - -Shouldn't it be 172.20.12.1 - 172.20.13.254 here? Where am I wrong?
IP Network and Broadcast ID = 172.20.11.0 and 172.20.12.255
Comments
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DCD
Member Posts: 475 ■■■■□□□□□□
Yes he is moving the subnet mask, It called VLSM.
16 :: CCNA R&S Exam Course :: IP Addressing, Subnetting, & VLSM - YouTube skip to the 37 minute mark. It not the best but it should help. -
TechGuru80
Member Posts: 1,539 ■■■■■■□□□□
Yes he is moving the subnet mask, It called VLSM.
16 :: CCNA R&S Exam Course :: IP Addressing, Subnetting, & VLSM - YouTube skip to the 37 minute mark. It not the best but it should help.
Good ole VLSM.
It's really not that bad but VLSM can hurt if you do not plan for the growth.
Start subnetting your largest amount...each will have its own subnet mask.
Figure for the number of hosts there WILL be total for each group. So 200 for the first etc. The largest will have the first subnet and then when that subnet ENDS, the next department's new network and subnet mask will START. Forgive me my brain is on weekend mode or else I would figure out the answer. As long as you understand how to subnet and understand go from largest to smallest it's not too bad.