CREATE TABLE table_149426_4 (available_subnets INT, network_mask VARCHAR)

When the network mask is 255.255.255.128 what is the lowest available subnet?
SELECT MIN(available_subnets) FROM table_149426_4 WHERE network_mask = "255.255.255.128"
SELECT MIN("available_subnets") FROM "table_149426_4" WHERE "255.255.255.128" = "network_mask"