Subnet mask Subnet mask bits Len Available ip-ranges (first=network, last=broadcast)
255.255.255.0 11111111.11111111.11111111.00000000 24 0-255
255.255.255.128 11111111.11111111.11111111.10000000 25 0-127, 128-255
255.255.255.192 11111111.11111111.11111111.11000000 26 0-63, 64-127, 128-191, 192-255
255.255.255.224 11111111.11111111.11111111.11100000 27 0-31, 32-63, 64-95, 96-127, 128-159, 160-191, 192-223, 224-255
255.255.255.240 11111111.11111111.11111111.11110000 28 0-15, 16-31, 32-47, 48-63, 64-79, 80-95, 96-111, 112-127, 128-143,
144-159, 160-175, 176-191, 192-207, 208-223, 224-239, 240-255
255.255.255.248 11111111.11111111.11111111.11111000 29 0-7, 8-15, 16-23, 24-31, 32-39, 40-47, 48-55, 56-63, 64-71, 72-79,
80-87, 88-95, 96-103, 104-111, 112-119, 120-127, 128-135, 136-143,
144-151, 152-159, 160-167, 168-175, 176-183, 184-191, 192-199,
200-207, 208-215, 216-223, 224-231, 232-239, 240-247, 248-255
255.255.255.252 11111111.11111111.11111111.11111100 30 0-3, 4-7, 8-11, 12-15, 16-19, 20-23, 24-27, 28-31, 32-35, 36-39,
40-43, 44-47, 48-51, 52-55, 56-59, 60-63, 64-67, 68-71, 72-75,
76-79, 80-83, 84-87, 88-91, 92-95, 96-99, 100-103, 104-107,
108-111, 112-115, 116-119, 120-123, 124-127, 128-131, 132-135,
136-139, 140-143, 144-147, 148-151, 152-155, 156-159, 160-163,
164-167, 168-171, 172-175, 176-179, 180-183, 184-187, 188-191,
192-195, 196-199, 200-203, 204-207, 208-211, 212-215, 216-219,
220-223, 224-227, 228-231, 232-235, 236-239, 240-243, 244-247,
248-251, 252-255
255.255.255.254 11111111.11111111.11111111.11111110 31  
255.255.255.255 11111111.11111111.11111111.11111111 32