Changing subnet mask

as long as none of the machines connect to the www you can assign any ip or subnet mask but if you plan on connecting through to the www you can only use 192.168.0.0 thru 192.168.255.255 and 10.0.0.0 thru 10.255.255.255 all others are reserved and issued by www admin. If you look at your above stated ip range and mask, your network is currently class 'c' with 254 maximum nodes and no www access allowed. To maintain it under these circumstances you can change the subnet mask to 255.255.0.0 on all machine nodes and thusly expand to allow 16382 nodes ranging 1.0.0.1 thru 1.0.255.254 but I would personally suggest you comply to speck and change the 1.0.0.x nodes to 192.168.0.x thru 192.168.255.x so you have a true class 'b'. As for what to change I recommend you set the default gateway if your using routers/bridges to always use 192.168.x.1 and reserve your machines to the range 192.168.x.2 thru 192.168.x.254

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hope this helps
rick

My answer is far different from the one above. I will assume that the Internet access is not an issue. Like the poster said, you can use any IP inside, I'll assume that you NAT outbound traffic to a public addresss(es), so internal IPs are not an issue. Whether you use 192.168 or 1.0 makes no difference, only the public IPs make a difference.

SInce you stated you use 1.0.0.1-1.0.0.254, changing your subnet mask will not be very painful since, in reality, you are using a range of addresses that correspond to the mask 255.0.0.0, 255.255.0.0, or 255.255.255.0. For instance, if you have an IP at a workstation at 1.0.0.2 mask 255.255.255.0 and your connecting to a device at 1.0.0.3 mask 255.255.0.0, they will still conect since they are both fall in the same subnet.

With your current mask, you can use 1.0.0.1-1.0.0.255 (253 usable addresses). With a mask of 255.255.0.0, you can use 1.0.0.1-1.0.255.254 (65023 addresses).

If you change your mask, change it on all devices, just to be consistent.

Simple answer - the subnet mask on all the devices in a subnet MUST be the same or you can run into some problems with what they will or will not recognise. It matters not if the mask is 255.255.255.0 or 255.255.0.0 or 255.0.0.0 what is important is that all the machines in that subnet have the same mask.

YES all routers and gateways must have their ports configured to match the subnet that they are attached to via that port.

You can have different masks in different subnets but need a router or gateway with two addressable ports, one on each subnet, that is configured for each subnet.

Although subnet masks are usually set to divide at each byte point they can be set to divide within a byte but this is harder to work out as it must be done based on the binary figures within the byte.

All a subnet mask does is define how many hosts the network sees as belonging to it, and then allows them to talk readily to each other but insists anything else must go to a gateway.

You cna use any IP address range that you want internally provided that you have some sort of gateway between you and the Internet and use Network Address Translation (NAT) in that gateway. Otherwise you have to apply for and get a public IP address class licence to suit your network. Better to set up a router or gateway with NAT and just use the IP address assigned by your ISP.

Three specific address groups have been reserved solely for internal use. It is recommended that you use these as the Internet routers etc are set up NOT to forward on address within these ranges, thus if any traffic gets out by accident it gets dumped at the first router. The internal groups are:

Class C 192.168.0.x for small networks 254 hosts max, mask is usually 255.255.255.0

Class B 172.1.x.x for bigger networks 65,020 hosts max, mask is usually 255.255.0.0

Class A 10.0.0.0 for large networks 16,645,120 hosts max, mask is usually 255.0.0.0