subnet 192.168.10.0 netmask 255.255.255.0
{
        dynamic-dhcp range 192.168.10.10 192.168.10.254
        {
                option subnet-mask 255.255.255.0;
                option broadcast-address 192.168.10.255;
                option routers 192.168.10.1;
                option dhcp-lease-time 30000;
                option domain-name-servers 8.8.8.8;
                option domain-name "testlab";
        }
}

subnet 192.168.11.0 netmask 255.255.255.0          
{                                                  
        dynamic-dhcp range 192.168.11.10 192.168.11.254
        {                                              
                option subnet-mask 255.255.255.0;      
                option broadcast-address 192.168.11.255;
                option routers 192.168.11.1;            
                option dhcp-lease-time 30000;           
                option domain-name-servers 8.8.8.8;     
                option domain-name "testlab";           
        }                                                       
}    

subnet 192.168.12.0 netmask 255.255.255.0               
{                                                       
        dynamic-dhcp range 192.168.12.10 192.168.12.254 
        {                                               
                option subnet-mask 255.255.255.0;       
                option broadcast-address 192.168.12.255;
                option routers 192.168.12.1;            
                option dhcp-lease-time 30000;           
                option domain-name-servers 8.8.8.8;     
                option domain-name "testlab";           
        }                                                                                                  
}