user: Question: When the network mask is  255.255.255.128 what is the lowest available subnet?
Columns: ['Prefix size', 'Network mask', 'Available subnets', 'Usable hosts per subnet', 'Total usable hosts']
Types: ['text', 'text', 'real', 'real', 'real']
Sample row: ['/24', '255.255.255.0', 1.0, 254.0, 254.0]
SQL:

assistant: SELECT MIN("Available subnets") FROM "Table" WHERE "Network mask" = '255.255.255.128';