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標題: IP Subnet (Anyone able to help me with my assignment?) hehe [打印本頁]
作者: et1984    時間: 2012-2-14 22:37     標題: IP Subnet (Anyone able to help me with my assignment?) hehe

Sorry I just started studying IP subnetting and VLSM
I have a few questions for subnetting, just wondering if someone can give me a hand ^_^
this is what I have to do..

I know using online subnet calculator should work but instead of using such thing I rather understand how to calculate it step by step.  I got this as my own answer but I'm not sure if it is right "256 subnets and 254 hosts"

The professionals can you give me a hand? ^_^ thanks
作者: mcjohnjohn    時間: 2012-2-14 22:53

65536 subnets and 254 hosts for each subnet
作者: et1984    時間: 2012-2-14 23:12

65536 subnets and 254 hosts for each subnet
mcjohnjohn 發表於 2012-2-14 22:53



how did 65536  being calculated? mind giving me an idea if it's too much to write?
作者: Prelude    時間: 2012-2-15 00:28

256 * 256?
作者: Prelude    時間: 2012-2-15 00:30

10.xxx.xxx.yyy

yyy are the available hosts for xxx.xxx subnet.
there are only 256 in each octet => 256 different yyy's.
xxx.xxx = 256 x 256.
作者: mcjohnjohn    時間: 2012-2-15 01:10

how did 65536  being calculated? mind giving me an idea if it's too much to write?
et1984 發表於 2012-2-15 15:12

example class A: 10.x.x.x
example class C: 10.0.0.x
as a result, 1 class A = 256*256 = 65536 class C
for each subnet, the first and last IP addresses are reserved, so each subnet can have 256-2 = 254 hosts

sorry for my laziless in previous post.
作者: et1984    時間: 2012-2-15 01:50

I think I get it....so if it's a class A 10.0.0.0 with a class b mask then it'll be reversed 254*254 hosts and 256 subnets?

arg I shouldn't take database and network at the same thing I kept on thinking of my ERD at this moment because I have a project to hand in tomorrow but my network homework needed to be handed in the day after

Thanks a lot guys hopefully I didn't annoy you guys if I didn't fully understand and kept on asking.
作者: et1984    時間: 2012-2-15 13:30

ah...so there's no complicated calculation like 2 to the power of how many host and net bits just simple calculations between the octets.
作者: mcjohnjohn    時間: 2012-2-15 18:41

I think I get it....so if it's a class A 10.0.0.0 with a class b mask then it'll be reversed 254*254 ...
et1984 發表於 2012-2-15 17:50

if class A -> class B, it should be:
1. 256 subnet
2. 256*256 - 2 hosts =  65534 (Not 254*254)
作者: et1984    時間: 2012-2-15 22:37

ah ! right! thanks thanks....sigh just a simple mistake will ruin the whole network....
作者: mcjohnjohn    時間: 2012-2-15 22:44

ah ! right! thanks thanks....sigh just a simple mistake will ruin the whole network....
et1984 發表於 2012-2-16 14:37

don't mention it la, we are LYK ar ma.
作者: et1984    時間: 2012-2-16 00:34

just wonna confirm I didn't get it wrong again so let's say my first question
class A ---> class c
10.0.0.0 with class c mask so the first subnet id will be 10.0.0.0 and the first host ip will be 10.0.0.1 last host ip for that subnet will be 10.0.0.254
10.0.1.0 will be the 2nd subnet id and first host ip for it will be 10.0.1.1 and so on....

right? ^_^
作者: mcjohnjohn    時間: 2012-2-16 00:39

just wonna confirm I didn't get it wrong again  so let's say my first question
class A ---> class  ...
et1984 發表於 2012-2-16 16:34

Great job! I always say that LYK members are all talent and genius, and you are definitely one of them!
作者: et1984    時間: 2012-2-16 01:23

Great job! I always say that LYK members are all talent and genius, and you are definitely one of t ...
mcjohnjohn 發表於 2012-2-16 00:39



haha too early to say that yet....that's only one question of my assignment and there are 5 more questions....and I have to hand them in tomorrow....hopefully I can and WILL know how to do them tomorrow morning haha....
I guess for that question I concentrated too much on those power of 2 stuffs because in class we did few questions and we always use the power of 2 so I kept on thinking about power of 2 with that class a with class c mask question....

again....thanks a lot mcjohnjohn ^_^ and prelude ^_^ I might bother you 2 again sometime soon hahaha...hope you guys don't mind !~!
作者: et1984    時間: 2012-2-16 14:42

How many subnets can you make if you want to break up the 200.1.200.0 network into pieces that contain 30 pc’s in each segment?

Am I getting on the right track that it should be only 4 subnets because for 30pcs we need at least 6 host bits each time since 5 host bits will be too less.
作者: mcjohnjohn    時間: 2012-2-16 19:26

How many subnets can you make if you want to break up the 200.1.200.0 network into pieces that conta ...
et1984 發表於 2012-2-17 06:42

just need 5 octets for 30 hosts.
2^5 =32, remove the first and last IP address, there are 30 IP addresses
if 200.1.200.0 is a class C network, it can have 2^3 = 8 subnets for 30 hosts
作者: et1984    時間: 2012-2-16 23:14

just need 5 octets for 30 hosts.
2^5 =32, remove the first and last IP address, there are 30 IP add ...
mcjohnjohn 發表於 2012-2-16 19:26



Hehe....I guess the instructor is asking for real life situation because it is right for 5 bits for 30 hosts but what about the network? it won't be enough so using 6 bits and I got the answer right with 4 subnets hehe...congratz me hehe...

but I think I'll need your help with a few questions because I'm having a midterm next week and he is gonna give us some questions to do but guess what...NO ANSWERS!!!!! so I won't even know if I'm on the right track or not
hope you don't mind....

P.S. stupid firefox wouldn't let me reply kept on telling me about this site attacked people with viruses >.<"
作者: mcjohnjohn    時間: 2012-2-16 23:28

Hehe....I guess the instructor is asking for real life situation because it is right for 5 bits f ...
et1984 發表於 2012-2-17 15:14

real life situation rocks! hahaha
作者: et1984    時間: 2012-2-17 01:12

real life situation rocks! hahaha
mcjohnjohn 發表於 2012-2-16 23:28



I know haha....and in class today he even mentioned becareful...better ask if they'll need an ip for wireless printer and all other stuffs because those people don't know internet as much as we do so so can' t just assign them with the minumun requirement hahaha
作者: et1984    時間: 2012-2-17 01:16

this is the question I have but he wouldn't give us answers

ABC Company has been assigned two class “C” networks of 221.230.78.0/24 and 221.230.79.0/24 by Internic. ABC Company has many small offices located throughout the lower mainland and wishes to interconnect all these offices together. The main office in Vancouver requires 100 host address space and all 30 remote offices require 5 hosts each. The offices will use fixed Wide-Area Links (to ensure secure communications) to the main office. The fixed links do not require IP addresses. Determine an addressing scheme for the ABC Company. Use names such as “office #1”, “office #2 …..

what I get for the first ip is of course 221.230.78.1/25 and 221.230.78.1/25 for the first net id
first for the office will be 221.203.78.129/28 for first ip for the office and net id will be 221.203.78.128/28

not sure if he will want us to write all the ip for the 30 offices....the one after the previous one what I get is 221.203.78.136/28 for net id first ip will be 221.203.78.137/28
and the 30th one I believe is 221.203.79.104/28.

Am I right on those? ^_^ hehe....sigh.....he won't post the answer and the midterm is next week



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