# Network Quick Reference


## Class Quick Reference

| **Class** | **Bits** | **Start** | **End**         | **Networks** | **Default Mask** | **CIDR** |
| --------- | -------- | --------- | --------------- | ------------:| ---------------- | -------- |
| A         | 0        | 0.0.0.0   | 127.255.255.255 |          128 | 255.0.0.0        | /8       |
| B         | 10       | 128.0.0.0 | 191.255.255.255 |        16384 | 255.255.0.0      | /16      |
| C         | 110      | 192.0.0.0 | 223.255.255.255 |      2097152 | 255.255.255.0    | /24      |
| D (mcast) | 1110     | 224.0.0.0 | 239.255.255.255 |      _undef_ | _undef_          | _undef_  |
| E (rsrvd) | 1111     | 240.0.0.0 | 255.255.255.255 |      _undef_ | _undef_          | _undef_  |


## Netmask Quick Reference

| **Bits** | **Total Hosts**   | **Usable** | **Netmask**     | **Inverse Mask** |
| -------- | -----------------:| -----------| --------------- | ----------------:|
| `/0`     | 4294967296 (2^32) | 4294967294 | 0.0.0.0         |  255.255.255.255 |
| `/1`     | 2147483648 (2^31) | 2147483646 | 128.0.0.0       |  127.255.255.255 |
| `/2`     | 1073741824 (2^30) | 1073741822 | 192.0.0.0       |   63.255.255.255 |
| `/3`     |  536870912 (2^29) | 536870910  | 224.0.0.0       |   31.255.255.255 |
| `/4`     |  268435456 (2^28) | 268435454  | 240.0.0.0       |   15.255.255.255 |
| `/5`     |  134217728 (2^27) | 134217726  | 248.0.0.0       |    7.255.255.255 |
| `/6`     |   67108864 (2^26) | 67108862   | 252.0.0.0       |    3.255.255.255 |
| `/7`     |   33554432 (2^25) | 33554430   | 254.0.0.0       |    1.255.255.255 |
| `/8`     |   16777216 (2^24) | 16777214   | 255.0.0.0       |    0.255.255.255 |
| `/9`     |    8388608 (2^23) | 8388606    | 255.128.0.0     |    0.127.255.255 |
| `/10`    |    4194304 (2^22) | 4194302    | 255.192.0.0     |     0.63.255.255 |
| `/11`    |    2097152 (2^21) | 2097150    | 255.224.0.0     |     0.31.255.255 |
| `/12`    |    1048576 (2^20) | 1048574    | 255.240.0.0     |     0.15.255.255 |
| `/13`    |     524288 (2^19) | 524286     | 255.248.0.0     |      0.7.255.255 |
| `/14`    |     262144 (2^18) | 262142     | 255.252.0.0     |      0.3.255.255 |
| `/15`    |     131072 (2^17) | 131070     | 255.254.0.0     |      0.1.255.255 |
| `/16`    |      65536 (2^16) | 65534      | 255.255.0.0     |      0.0.255.255 |
| `/17`    |      32768 (2^15) | 32766      | 255.255.128.0   |      0.0.127.255 |
| `/18`    |      16384 (2^14) | 16382      | 255.255.192.0   |       0.0.63.255 |
| `/19`    |       8192 (2^13) | 8190       | 255.255.224.0   |       0.0.31.255 |
| `/20`    |       4096 (2^12) | 4094       | 255.255.240.0   |       0.0.15.255 |
| `/21`    |       2048 (2^11) | 2046       | 255.255.248.0   |        0.0.7.255 |
| `/22`    |       1024 (2^10) | 1022       | 255.255.252.0   |        0.0.3.255 |
| `/23`    |        512 (2^9)  | 510        | 255.255.254.0   |        0.0.1.255 |
| `/24`    |        256 (2^8)  | 254        | 255.255.255.0   |        0.0.0.255 |
| `/25`    |        128 (2^7)  | 126        | 255.255.255.128 |        0.0.0.127 |
| `/26`    |         64 (2^6)  | 62         | 255.255.255.192 |         0.0.0.63 |
| `/27`    |         32 (2^5)  | 30         | 255.255.255.224 |         0.0.0.31 |
| `/28`    |         16 (2^4)  | 14         | 255.255.255.240 |         0.0.0.15 |
| `/29`    |          8 (2^3)  | 6          | 255.255.255.248 |          0.0.0.7 |
| `/30`    |          4 (2^2)  | 2          | 255.255.255.252 |          0.0.0.3 |
| `/31`    |          2 (2^1)  | 0          | 255.255.255.254 |          0.0.0.1 |
| `/32`    |          1 (2^0)  | 1          | 255.255.255.255 |          0.0.0.0 |