/19 subnets
0-31
([12]?[0-9]|3[01])
32-63
(3[2-9]|[45][0-9]|6[0-3])
64-95
(3[2-9]|[45][0-9]|6[0-3])
64-95
(6[4-9]|[78][0-9]|9[0-5])
96-127
(9[6-9]|1[01][0-9]|12[0-7])
128-159
(12[89]|1[3-5][0-9])
160-191
(1[6-8][0-9]|19[01])
192-223
(19[2-9]|2[01][0-9]|22[0-3])
224-255
(22[4-9]|2[34][0-9]|25[0-5])
96-127
(9[6-9]|1[01][0-9]|12[0-7])
128-159
(12[89]|1[3-5][0-9])
160-191
(1[6-8][0-9]|19[01])
192-223
(19[2-9]|2[01][0-9]|22[0-3])
224-255
(22[4-9]|2[34][0-9]|25[0-5])