Different subnet masks in general. Company A may be pretty straightforward and have subnet masks of 255.255.255.0.

An Example of Subnetting Take a class A IP address with the format network.node.node.node for example. We can use this to create a subnet.

I know that one office would have to be (for example) 10.0.0.x and the other office would have to be 10.0.1.x. In this case, what should the subnet mask be for the network on either side of the VPN?

One of the most prevalent problems with IP networks occurs when IP subnet masks are incorrect. This seems to happen frequently because the concept of the subnet mask is not understood accurately. In ...

For example, in order to stipulate a specific IP address, that address would be accompanied by a wildcard mask of 0.0.0.0. To refer to all packets with Class A addresses in the 10.10.x.x range ...

Type your subnet mask into cells B1 through B4, tying each byte into a separate cell. Continuing the example, type "255" into cell B1, "255" into B2, "255" into B3 and "224" into B4.