IP Address Classes
|
Address Class |
First Octet Value |
Number of Hosts Per Subnet |
|
A |
0-127 |
16,777,214 |
|
B |
128-191 |
65,534 |
|
C |
192-223 |
254 |
|
D |
224-239 |
Reserved for Multicasting |
|
E |
240 – 254 |
Experimental; used for research |
Note: Class A addresses 127.0.0.0 to 127.255.255.255 cannot be used and is reserved for loopback and diagnostic functions.
Class Ranges of Network IDs
|
Address Class |
First Network ID |
Last Network ID |
|
Class A |
1.0.0.0 |
126.0.0.0 |
|
Class B |
128.0.0.0 |
191.255.0.0 |
|
Class C |
192.0.0.0 |
223.255.255.0 |
Private IP Addresses
|
Class |
Private Networks |
Subnet Mask |
Address Range |
|
A |
10.0.0.0 |
255.0.0.0 |
10.0.0.0 – 10.255.255.255 |
|
B |
172.16.0.0 – 172.31.0.0 |
255.240.0.0 |
172.16.0.0 – 172.31.255.255 |
|
C |
192.168.0.0 |
255.255.0.0 |
192.168.0.0 – 192.168.255.255 |
Binary Table
|
28 |
27 |
26 |
25 |
24 |
23 |
22 |
21 |
20 |
|
256 |
128 |
64 |
32 |
16 |
8 |
4 |
2 |
1 |
Mask Table
|
Binary |
Mask |
Addresses |
|
00000000 |
0 |
256 |
|
10000000 |
128 |
128 |
|
11000000 |
192 |
64 |
|
11100000 |
224 |
32 |
|
11110000 |
240 |
16 |
|
11111000 |
248 |
8 |
|
11111100 |
252 |
4 |
|
11111110 |
254 |
2 |
|
11111111 |
255 |
1 |
Class A (24 bits available for subnetting)
|
Bits Required |
Subnets (2n-2) |
Hosts Per Subnet (2h-2) |
Slash Notation |
Mask |
Subnet Slice |
|
1 |
21 – 2 = 0 |
223 – 2 = 8,388,606 |
/9 |
255.128.0.0 |
Subnet 0 |
|
2 |
22 – 2 = 2 |
222 – 2 = 4,194,302 |
/10 |
255.192.0.0 |
Subnet 1/7 |
|
3 |
23 – 2 = 6 |
221 – 2 = 2,097,150 |
/11 |
255.224.0.0 |
Subnet 2/7 |
|
4 |
24 – 2 = 14 |
220 – 2 = 1,048,574 |
/12 |
255.240.0.0 |
Subnet 3/7 |
|
5 |
25 – 2 = 30 |
219 – 2 = 524,286 |
/13 |
255.248.0.0 |
Subnet 4/7 |
|
6 |
26 – 2 = 62 |
218 – 2 = 262,142 |
/14 |
255.252.0.0 |
Subnet 5/7 |
|
7* |
27 – 2 = 126 |
217 – 2 = 131,070 |
/15 |
255.254.0.0 |
Subnet 6/7 |
|
8* |
28 – 2 = 254 |
216 – 2 = 65,534 |
/16 |
255.255.0.0 |
Subnet 7/7 |
*7 subnets valid for Class A
Class B (16 bits available for subnetting)
|
Bits Required |
Subnets (2n-2) |
Hosts Per Subnet (2h-2) |
Slash Notation |
Mask |
Subnet Slice |
|
1 |
21 – 2 = 0 |
215 – 2 = 32,766 |
/17 |
255.255.128.0 |
Subnet 0 |
|
2 |
22 – 2 = 2 |
214 – 2 = 16,382 |
/18 |
255.255.192.0 |
Subnet 1/7 |
|
3 |
23 – 2 = 6 |
213 – 2 = 8,190 |
/19 |
255.255.224.0 |
Subnet 2/7 |
|
4 |
24 – 2 = 14 |
212 – 2 = 4,094 |
/20 |
255.255.240.0 |
Subnet 3/7 |
|
5 |
25 – 2 = 30 |
211 – 2 = 2,046 |
/21 |
255.255.248.0 |
Subnet 4/7 |
|
6 |
26 – 2 = 62 |
210 – 2 = 1,022 |
/22 |
255.255.252.0 |
Subnet 5/7 |
|
7* |
27 – 2 = 126 |
29 – 2 = 510 |
/23 |
255.255.254.0 |
Subnet 6/7 |
|
8* |
28 – 2 = 254 |
28 – 2 = 254 |
/24 |
255.255.255.0 |
Subnet 7/7 |
*7 subnets valid for Class B
Class C (8bits available for subnetting)
|
Bits Required |
Subnets (2n-2) |
Hosts Per Subnet (2h-2) |
Slash Notation |
Mask |
Subnet Slice |
|
1 |
21 – 2 = 0 |
215 – 2 = 126 |
/25 |
255.255.255.128 |
Subnet 0 |
|
2 |
22 – 2 = 2 |
214 – 2 = 62 |
/26 |
255.255.255.192 |
Subnet 1/5 |
|
3 |
23 – 2 = 6 |
213 – 2 = 30 |
/27 |
255.255.255.224 |
Subnet 2/5 |
|
4 |
24 – 2 = 14 |
212 – 2 = 14 |
/28 |
255.255.255.240 |
Subnet 3/5 |
|
5* |
25 – 2 = 30 |
211 – 2 = 6 |
/29 |
255.255.255.248 |
Subnet 4/5 |
|
6* |
26 – 2 = 62 |
210 – 2 = 2 |
/30 |
255.255.255.252 |
Subnet 5/5 |
*5 subnets valid for Class C; last 2 are binary all 1