I believe that warning is only informational.
What it means is that the dhcp server will NOT give out IPs to requests from the internet side (on the external interface).
So it shouldn't be a problem
From what I could understand your internet access is through eth0? (with ip 192.168.2.2)
The declaration of the external net (192.168.2.0) has no subnetmask defined in the dhcpd.conf, and thus has no idea of what broadcast address to use.
So the log message just states that it can not use eth0 for distributing ips (which is what you want, from what I can understand).