How do I tell if computers are on the same network?

Question

Hi, I have just begun a networking course, so its all new to me!

here is a hyperthetical example I have been given but don't know how to answer!

Computer 1

ip address: 192.168.12.113
subnet mask: 255.255.255.0
default gateway: 192.168.12.1

Computer 2

ip address:192.168.12.205
subnet mask: 255.255.255.0
default dateway: 192.168.12.1

Computer 3

ip address: 192.168.112.97
subnet mask: 255.255.255.0
default gateway: 192.168.12.1

Using this information I have to answer if all these computers are on the same network and explain my answer.

It then goes on to ask, if something is wrong, what is likely to be the problem?

Please help, thanks in advance Matt!

Answer 1

Computers 1 and 2 are on the same network, computer 3 is on a different network. This is basically a subnetting question. Look carefully at the subnet numbers. You have 192.168.12 for computers 1 and 2, but 192.168.112 for computer 3. The subnet mask is 255.255.255.0 for all 3, and the default gateway is 192.168.12.1 for all 3. Computer 3 is misconfigured. It cannot have a 24-bit subnet mask (255.255.255.0) and have a default gateway on a different subnet. The result is that computers 1 and 2 will be able to communicate, but computer 3 is cut off. If the subnet of computer 3 is changed from 112 to 12, you're good to go.

Answer 2

Make sure they have all the same workgroup name the default "mshome' if you running a server then they all have to be in the same domain and all right to each computers are = to each other