CREATE TABLE table_46699 ("Class" TEXT, "Leading bits" FLOAT, "Size of network number bit field" TEXT, "Size of rest bit field" TEXT, "Number of networks" TEXT, "Addresses per network" TEXT, "Start address" TEXT, "End address" TEXT)

What is the start address when the network number bit field is 16?
SELECT "Start address" FROM table_46699 WHERE "Size of network number bit field" = '16'
SELECT "Start address" FROM "table_46699" WHERE "Size of network number bit field" = '16'