hunting for network number

[Chris]

Is there a way to find out the subnet no (not subnet
mask) on a local area network?

 

[Chris]

So, how do I go about doing this? Perhaps using a free
program?

I've converted the ip address and subnet mask both to
binary format, as shown below.

192.168.1.100 - 11000000.10101000.10000000.01000100
255.255.255.0 - 11111111.11111111.11111111.00000000

Where do I go from there?

 

[Kureli]

Now when u AND the two nos.. you will get

192.168.1.100 - 11000000.10101000.10000000.01000100
255.255.255.0 - 11111111.11111111.11111111.00000000

____________________________________________________
11000000.10101000.10000000.00000000

Which equals to 192.168.1.0
You started with 192.168.1.100 but, u got 3 octets the
same but the last one is 0 istead of 100

so, you are in the sub-net 192.168.1.0/24 or in the
network 192.168.1.0 with a class C mask.
Got it??

 

[Chris]

so, you are in the sub-net 192.168.1.0/24

I do understand most of what you said though except for
this. I don't understand how you got the 24. How did you
get that one?

 

[Kureli]

I got the 24 from 255.255.255.0 out of 8+8+8+8 = 32 bits u
are using 24 bits (8+8+8) bits for your mask.
Got it?

 

[Chris]

Okay I think I got. You really don't need to know the IP
address and subnet mask into binary, compare the two
addresses and etc. Just take the subnet mask as you
pointed out and you should be able to do the rest.

255.255.0.0 - 8 + 8 = 16 bits or 255.255.0.0/16