Computer Networking Question?

Question

Networking is not my strong point (I have done very basic networking etc) so here is a simple question for those who know it a lot better than me so basically I think I understand the basic concept but correct me were I am wrong as I need to know.

So basically a subnet mask is 255.255.255.0 

So am I right in saying if an IP address is set to for example 195.168.2.1 according to the subnet mask this should lock in the first 3 sets of numbers to identify a network and only computers connected to my LAN can access this eg 195.168.2.XX can access the network but 195.168.1.2 could not access the network. 

Am I also right in saying if a subnet mask is set to 255.255.255.0 a maximum of 225 computers could technically be networked to the ip address starting 195.168.2.xx (up to 225)

Now if Im right so far (I hope I am) but I think I am going to be wrong here, what if the subnet was changed on another computer network to 255.255.0.0 and the IP address was set on one of its devices to 195.168.2.13 could this computer access the network with the Subnet of 255.255.255.0 but any computers with this subnet 255.255.255.0 could not access the computers with the subnet 225.225.225.0 as the IP address of that other computers on that network as there devices could have IP addresses of 192.168.7.10 but if an IP address was set to match the first 3 sets of numbers in 195.168.2.xx those computers could communicate  and other computers on the other network could not eg 192.168.12.12

I hope I you can understand what I mean in the above is wrong please correct me.

Krowten Nimda · Accepted Answer

"only computers connected to my LAN can access this eg 195.168.2.XX can access the network but 195.168.1.2 could not access the network."

Not really. You are correct that devices on your LAN will have IP addresses of 195.168.2.1-254. Whether devices in another network can access those device is determined by other factors, like if there is a route to and from both networks, access restrictions, firewalls, etc. But basically, as long as their is a route to a network, devices in other networks can reach them.

"Am I also right ...."

No. As I stated above, the host addresses would be 195.168.2.1-254. The host addresses equals the number of host bits available minus 2; one for the network address (first IP address in network) and the broadcast address (last IP address). So in your example, the mask is 255.255.255.0. That means we have 8 bits to address hosts with. 2^8=256. We start at 0, so the values are 0-255. The first address is 195.168.2.0 and is the network address. The broadcast is the last address, or 195.168.2.255. This leaves 254 address left to use.

"Now if Im right so far..."

You kinda lost me on this one, but I think I get the gist of your question. Yes, you can flub the subnet mask, and it will work within the LAN as long as the host with the incorrect settings has an IP address that is in the correct subnet and the gateway address is correct for that network. However, if you set the IP address to be outside of the bounds of the subnet, it won't work as the all the devices will believe you are on a different IP network. I'm not exactly sure what they'll, but at some point the packet is going to get dropped.

Good Questions.

hanrahan · Answer

to establish your guy or woman wifi community, what's your router? it is your router that establishes your on the spot community.. as quickly as set up, you have your guy or woman on the spot community - uncomplicated as that...

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Computer Networking Question?

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