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# Help me out whit IP and Subnetting

Registered Users Posts: 4 ■□□□□□□□□□
I have a test tomorrow that i cant fail its about IP and subnetting, i was wondering if someone on this forum could fill out one of the practice situations whit some information on how you did it so i can do the other practice situations that i got from my teacher myself,

These are the situations:

A company has 192.169.0.1 as IP and wants to devide theyre network in 5 subnets
what is the class? (i know this no explaination needed)
what is the standard subnetmask? (This too)
how much bits have to be reserved?
What is the prefix?
Is said IP adress a valid IP?

Then there is one more situation where the IP and the Subnet is given,

Number of subnet bits?
Number of subnets?
Number of host bits per subnet?
Number of useable host per subnet?
IP adress of the First host on this subnet?
IP adress of last host on this subnet?

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Mod Posts: 6,928 Mod
Welcome to TE. I hate to be that guy but if the test is tomorrow you should've asked for help earlier.

Have you tried the situations? Where did you get stuck? Say what you have done and where you hit a roadblock and I'm sure someone with better subnetting skills than mine will chime in.
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Mod Posts: 11,962 Mod
Tell us what you got and how you went about getting it and we can point you in the right direction.
An expert is a man who has made all the mistakes which can be made.
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Member Posts: 378 ■■□□□□□□□□

We know each IPV4 IP address is 32 bits long. ...Network+ SUBNET+HOST= 32 BITS

Class A =8 network bits
Class B =16 network bits
Class C =24 network bits

Calculate (H)Host = 32 - Prefix(P).

Once you find your Host and Network bits, you should be able to figure out the subnet..

x=bits

subnet= 2^x
host=2^x-2

also watch Danscourses.com video on subneting. It will blow your mind..

On a side note can't wait to move to ipv6. Seems like its easier to count in hex then in Dec
The Only way to do great work is to love what you do. If you haven't found it keep looking. Don't settle - Steve Jobs
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Registered Users Posts: 4 ■□□□□□□□□□
A company has 192.169.0.1 as IP and wants to devide theyre network in 5 subnets
what is the class? (i know this no explaination needed)
I know the classes and ranges that come whit it,
A= 0 -127 standard subnet is 255.0.0.0
B= 128 - 191 standard subnet is 255.255.0.0
C= 192 - 223 standard subnet 255.255.255.0
(d & e)
what is the standard subnetmask? (This too) i know i have to look at the first octet and match it whit a class.
how much bits have to be reserved?
i somewhat get this chart on bits and useable networks.

Bits
Networks
Useable networks

0
0
0

1
2
0

2
3
2

3
8
6

4
16
14

5
32
30

6
64
62

7
128
126

etc

i guess because i need 5 subnets i need to reserve 3 bits.
What is the NEW subnetmask? i really dont have a clue on this.
What is the prefix? i beleave i can figure this out if i manage to get the NEW subnetmask becaus i get the part whit 8 bits for an octet.
Is said IP adress a valid IP?
10.0.0.0
172.16.0.0
192.168.0.0
are special and cant be used, i guess because this doesnt match my situation it is a valid IP ? this is what i can do on the first situation.

edit; for the second situation, i really dont have a clue how to start.
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Member Posts: 1,569 ■■■■■■■□□□
Probably too late to help, but here is a Kindle book that flipped the switch for me, subnetting-wise. Amazon.com: IP Subnetting made Easy! eBook: John Kowalski: Kindle Store
Working on: staying alive and staying employed
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Member Posts: 378 ■■□□□□□□□□
ok to help you solve the IP part of the problem, google the "Magic NUmber trick Good LUck...
The Only way to do great work is to love what you do. If you haven't found it keep looking. Don't settle - Steve Jobs
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Registered Users Posts: 4 ■□□□□□□□□□
i watched 5 parts of the Danscourses.com on subnetting, i get how to read binary properly now, but i dont feel like this answers my question because in my situation you dont get the prefix, all the exaples given on dancoursesare have the prefix already given. I dont get how im supposed to find it whit the IP and the subnet amounts...

edit;
i think i might know it actually...
A company has 192.169.0.1 as IP and wants to devide theyre network in 5 subnets
5 subnets is 3 bits according to the graph above, its a class C adress so 255.255.255 is default

so my guess is that the new subnet would be 255.255.255.32 wich makes the prefix /27