Why does my Windows DHCP server hand out a non-configured subnet mask?

We run the DHCP server role on our domain controller (Windows SBS 2011).

We want our LAN subnet to be restricted 10.1.1.0/24 (unsure if this is the correct notation but our subnet to be restricted the address block 10.1.1.1–255)

We have manually set the DHCP scope as follows:

• Range: 10.1.1.1–255


• Sbnet mask: 255.255.255.0


• Default gateway: 10.1.1.1


• DNS server: 10.1.1.2

But for some reason Windows server defaults the scope description to: 10.0.0.0 and dynamically hands out subnet mask of 255.0.0.0
to client devices.

1. Why would the DHCP server be doing this? Have I missed something?

If my client devices are assigned with IP settings like:

• IP address: 10.1.1.10


• Subnet mask: 255.0.0.0


• Default gateway: 10.1.1.1


• DNS servers: 10.1.1.2 & 208.67.222.222

Then:

2. Would having all my LAN devices assigned subnet mask of 255.0.0.0 (even though I want the subnet to be 10.1.1.1–255) result in network address resolution problems?


3. What kind of problems could come about from using this subnet mask of 255.0.0.0 (instead of 255.255.255.0) ?