Broadcast address / changing subnet mask to full class C help need

Hi,

I'm working at a site that went from 1/2 a class C to a full class C. The
old subnet mask was 255.255.255.128 and now it is 255.255.255.0. The old
network address range was from 10.1.1.1 - 10.1.1.126. The new should be from
10.1.1.1 - 10.1.1.254.

I am just now figuring out that with the first subnet that address .127 is
reserved for broadcast. When we made the change, we are seeing errors with a
new machine set to 10.1.1.127 even though the subnet mask for that machine is
255.255.255.0.

How do we go about getting this IP ready for use? We're working on getting
all machines swapped to the subnet mask of 255.255.255.0, but if one machine
is still set to the old subnet mask will that stop this IP from working?

Thank you!

--Kent

Hello kentiler,

The machine will not react, different network. Do you use fixed ip's? Then
change them asap. For DHCP delete the old scope and create a new one. Then
reboot the clients so that they update correct.

Best regards

Meinolf Weber
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> Hi,
>
> I'm working at a site that went from 1/2 a class C to a full class C.
> The old subnet mask was 255.255.255.128 and now it is 255.255.255.0.
> The old network address range was from 10.1.1.1 - 10.1.1.126. The new
> should be from 10.1.1.1 - 10.1.1.254.
>
> I am just now figuring out that with the first subnet that address
> .127 is reserved for broadcast. When we made the change, we are seeing
> errors with a new machine set to 10.1.1.127 even though the subnet
> mask for that machine is 255.255.255.0.
>
> How do we go about getting this IP ready for use? We're working on
> getting all machines swapped to the subnet mask of 255.255.255.0, but
> if one machine is still set to the old subnet mask will that stop this
> IP from working?
>
> Thank you!
>
> --Kent
>