d-i netcfg/disable_autoconfig boolean true
d-i netcfg/get_nameservers string 10.20.0.1
d-i netcfg/get_ipaddress string 10.20.0.2
d-i netcfg/get_netmask string 255.255.255.0
d-i netcfg/get_gateway string 10.20.0.1
d-i netcfg/confirm_static boolean true
d-i preseed/include string common.seed