Any networking experts out there that are clued up on subnetting????????

Question

Given the IP address 192.168.16.109 and the subnet mask 255.255.255.240.....

What is the network number?

What is the subnet number?

What is the host number

Answer 1

Network segment (not number) is: 192.168
Subnet mask is: 255.255.255.0
Host: 127.1.0.0

Answer 2

To create the subnet mask, first remember that the purpose of the subnet mask is to separate the (32 bit) IP address into the network prefix and the host number.

First depict the IP address in binary. Take 200.168.90.0 and convert it to binary.

IP address: 11001000.10101000.01011010.00000000

First we determine what class of address it is:
If the first bit is 0 it is a class A address.
If the first two bits are 10 it is a class B address
If the first three bits are 110 it is a class C address
If the first four bits are 1110 it is a class D address
If the first four bits are 1111 it is a class E experimental address.
Our example is a class C address. Since we want to subnet as a Class C. the default subnet mask would be:

Subnet mask: 11111111.11111111.11111111.00000000 (255.255.255.0)

The formula for figuring out the number of ‘network’ bits in a subnet is:
2^n = number of subnets (2^n means ‘2’ to the power of ‘n’)
Since we know the number of subnets, we need to find ‘n’.
Because we want 16 subnets we want to add 4 – ‘1’ bits to the default subnet mask
(16 = 2^4) This will give us the following subnet mask:

Subnet mask 11111111.11111111.11111111.11110000 (255.255.255.240)

We also need to be able to find the range of assignable IP addresses on this subnet. To do this, we take the binary that tells us the subnet address, in this case 00000000, and compare it with the subnet mask 11110000. 200.168.90.0 and 255.255.255.240
00000000 IP address last number
11110000 Subnet address last number
The bits covered by the mask we will leave as they are. The rest of the bits we make high. So:
00000000 = 0
11110000 = 240
-------------
00001111 = 15

So the first network would be 200.168.90.0 thru 200.168.90.15. The first and last IP address of each network cannot be used for nodes the first one is for network and the last one is the broadcast. So, the useable IP address for the network would be 200.168.90.1 thru 200.168.90.14. So we will have 14 IP address in each network. Let’s try it one more time:

The second network will be 200.168.90.16. So here it is;

00010000 = 16
11110000 = 240
-------------
00011111 = 31

So this range of IP address will be 200.168.90.16 thru 200.168.90.31. So, the useable IP address would be 200.168.90.17 thru 200.168.90.30.
So with this setup we will have 16 subnets with 14 useable IP address on each network.

Answer 3

Network number is 192.168.6.x
Host number is 13

to the best of my knowledge subnet number = network number.

The subnet mask is 11111111.11111111.11111111.11110000
If you AND the binary version of the given IP address against the mask the network/host addresses fall out.

In binary 109 = 01101101
AND 11110000 with 01101101

0110 = 6
1101 = 13

Answer 4

A subnet mask defines how many bits of an IP adress to use for the network/subnet ID's and how many bits to use for the host ID.

the length for the subnet you gave is 28

But to calculate all options, more info is needed. Start ip adress / end ip adress for the DHCP and if it's locked to 1 subnet..

EDIT : the microsoft exam suite 70-291 has a part concerning subnetting and tcpip adresses...

Answer 5

network number: 192.168.16.109
subnet number: 255.255.255.240
host number: not given. i would guess 192.168.16.1

Answer 6

well the mask of 240 is the key
you AND that with 109 and get 96 address that can come through