IP subnet question! pt. 3

[Ropy]

Given the IP address 112.85.6.200. You are required to create 1000 subnetwork that can host a minimum of 500 nodes per subnet.

::The following are required::
1. Default Subnet Mask
2. New Subnet Mask
3. Number of Borrowed Bits
4. 8 Subnetworks Including The Zero Subnet
5. Subnet ID, Boradcast ID and Host Range of Each 8 Networks

[zRo ToLeRaNcE]

1. 255.0.0.0
2. 255.255.240.0
3. 12 bits (get a nice ratio of subnets to hosts instead of 10. Also allows for growth)
4 & 5.


ID Host Range Broadcast
112.0.0.0 112.0.0.1 - 112.0.15.254 112.0.15.255
112.0.16.0 112.0.16.1 - 112.0.31.254 112.0.31.255
112.0.32.0 112.0.32.1 - 112.0.47.254 112.0.47.255
112.0.48.0 112.0.48.1 - 112.0.63.254 112.0.63.255
112.0.64.0 112.0.64.1 - 112.0.79.254 112.0.79.255
112.0.80.0 112.0.80.1 - 112.0.95.254 112.0.95.255
112.0.96.0 112.0.96.1 - 112.0.111.254 112.0.111.255
112.0.112.0 112.0.112.1 - 112.0.127.254 112.0.127.255


I'm having several doubts about my calculations here. I need to practice more.

[digitalchef]

zro_t u mind explaining how u got the answers??

[zRo ToLeRaNcE]

1. The address is a Class A address so i simply reply with a Class A subnett i.e. 255.0.0.0.

2&3. The number of borrowed bits question should have come before the new subnet question so i will answer in that way.
I decided to first borrow 10 bits from the class A address...therefore 255.1111111.11000000.00000000. That gave me 1022 subnets (i.e. 2^10-2) and 2^14-2 hosts (which should be close to 16K) Remember no calculator so i don't know the exact.
So i tried borrowing 11 then 12. It gave me close to 4000 subnets and 4000 hosts (approximately)
I tried the Juba posted in IP Addressing Quiz Pt 1 but it wasn't working for me so i went back to guestimation.
Therefore my choice of 12 bits. Now convert the bits back to decimal leaves us with 255.240 thus subnet 255.255.240.0

4. The first thing is then to find the block size which is 256-240 = 16. This starts the calculation. We use back the network portion and define the addresses.
Subnet 1 = 112.0.0.0
Range would go up by 16 therefore 112.0.16.0 but that address is actually the start of the next subnet so the end of the subnet would be 112.0.15.255. That address is also the broadcast address for the subnet.
THe hosts then go from 112.0.0.1 to 112.0.15.254 (i.e. 1 before the broadcast). The ID and the Broadcast are reserved addressed (thats why we subtract 2 from the calculations).

These calculation were explained in Part 1 of IP Addressing Quiz
http://www.techjamaica.com/forums/showpost.php?p=130047&postcount=14

[zRo ToLeRaNcE]

HeeelllllloooooOOOOO

Is true mi answer nobody want to tell me if mi right or wrong.

The last IP quiz everybody was saying "Damn, i wish i saw it earlier....open unno eyes!!"

[badboyziggy]

Zro tolerance I disagree you are using 12 bits for the subnets that is a bit too much you do realize that is 4096 subnets and the question asked for 1000, as well as 4094 hosts, its true you want to allow for growth but that is a bit too much growth if you ask me. Although im not sure if I am suppose to focus on the host side or the subnet side, in this case I will just focus on the subnet side.

Check out my solution.

1. 255.0.0.0
2. 255.255.192.0
3. 10 bits used for subnetting which gives 1024 subnets and 16382 hosts(way more than the minimum 500)

4 & 5.
Subnet ID
112.0.0.0
112.0.64.0
112.0.128.0
112.0.192.0
112.1.0.0
112.1.64.0
112.1.128.0
112.1.192.0

Host Range
112.0.0.1 - 112.0.63.254
112.0.65.1 - 112.0.127.254
112.0.129.1 - 112.0.191.254
112.0.193.1 - 112.0.255.254
112.1.0.1 - 112.1.63.254
112.1.65.1 - 112.1.127.254
112.1.129.1 - 112.1.191.254
112.1.193.1 - 112.1.255.254

Broadcast
112.0.63.255
112.0.127.255
112.0.191.255
112.0.255.255
112.1.63.255
112.1.127.255
112.1.191.255
112.1.255.255

If any of this is wrong feel free to correct it people.

[Ropy]

I forgot to post the answers... will try and do so tomorrow.

[AnthrAx]

it seems tomorrow will never get here for you lol, because that was from last year october

[Ropy]

it seems tomorrow will never get here for you lol, because that was from last year octoberI got busy and kinda forgot about this thread.:icon_frow

Anyways, badboyziggy was correct.

If zRo had used 10 instead of 12 he would have been too.