Semester 3 - Computer Networks - References
Power of 2s
| 2^7 | 2^6 | 2^5 | 2^4 | 2^3 | 2^2 | 2^1 | 2^0 |
|---|---|---|---|---|---|---|---|
| 128 | 64 | 32 | 16 | 8 | 4 | 2 | 1 |
Decimal, Binary & Hexadecimal
| Decimal | Binary | Hexadecimal |
|---|---|---|
| 0 | 0000 | 0 |
| 1 | 0001 | 1 |
| 2 | 0010 | 2 |
| 3 | 0011 | 3 |
| 4 | 0100 | 4 |
| 5 | 0101 | 5 |
| 6 | 0110 | 6 |
| 7 | 0111 | 7 |
| 8 | 1000 | 8 |
| 9 | 1001 | 9 |
| 10 | 1010 | A |
| 11 | 1011 | B |
| 12 | 1100 | C |
| 13 | 1101 | D |
| 14 | 1110 | E |
| 15 | 1111 | F |
Reference Table for Classes in IP4
| Class | Range | Default Subnet Mask | Network/Host Breakdown | Number of Networks | Number of Hosts per Network | Common Usage |
|---|---|---|---|---|---|---|
| A | 1.0.0.0 to 126.0.0.0 | 255.0.0.0 | N.H.H.H | 126 | 16,777,214 | Large multinational organizations |
| B | 128.0.0.0 to 191.255.0.0 | 255.255.0.0 | N.N.H.H | 16,384 | 65,534 | Medium-sized organizations |
| C | 192.0.0.0 to 223.255.255.255 | 255.255.255.0 | N.N.N.H | 2,097,152 | 254 | Small organizations, home networks |
| D | 224.0.0.0 to 239.255.255.255 | N/A | N/A | N/A | N/A | Multicast groups |
| E | 240.0.0.0 to 255.255.255.254 | N/A | N/A | N/A | N/A | Reserved for future use, research |
| CIDR | Subnet Mask | Total Addresses per Subnet | Wildcard/Range |
|---|---|---|---|
| /32 | 255.255.255.255 | 1 | 0.0.0.0 |
| /31 | 255.255.255.254 | 2 | 0.0.0.1 |
| /30 | 255.255.255.252 | 4 | 0.0.0.3 |
| /29 | 255.255.255.248 | 8 | 0.0.0.7 |
| /28 | 255.255.255.240 | 16 | 0.0.0.15 |
| /27 | 255.255.255.224 | 32 | 0.0.0.31 |
| /26 | 255.255.255.192 | 64 | 0.0.0.63 |
| /25 | 255.255.255.128 | 128 | 0.0.0.127 |
| /24 | 255.255.255.0 | 256 | 0.0.0.255 |
| /23 | 255.255.254.0 | 512 | 0.0.1.255 |
| /22 | 255.255.252.0 | 1024 | 0.0.3.255 |
| /21 | 255.255.248.0 | 2048 | 0.0.7.255 |
| /20 | 255.255.240.0 | 4096 | 0.0.15.255 |
| /19 | 255.255.224.0 | 8192 | 0.0.31.255 |
| /18 | 255.255.192.0 | 16384 | 0.0.63.255 |
| /17 | 255.255.128.0 | 32768 | 0.0.127.255 |
| /16 | 255.255.0.0 | 65536 | 0.0.255.255 |
| /15 | 255.254.0.0 | 131072 | 0.1.255.255 |
| /14 | 255.252.0.0 | 262144 | 0.3.255.255 |
| /13 | 255.248.0.0 | 524288 | 0.7.255.255 |
| /12 | 255.240.0.0 | 1048576 | 0.15.255.255 |
| /11 | 255.224.0.0 | 2097152 | 0.31.255.255 |
| /10 | 255.192.0.0 | 4194304 | 0.63.255.255 |
| /9 | 255.128.0.0 | 8388608 | 0.127.255.255 |
Formulas:
Total subnets = 2^bits borrowed
Block size or increment (for network identifier) = 256 - (interesting octet number)
Network /identifier or subnet id = first address of network
Broadcast address = last address of network
Total number of hosts = (2^bits left for hosts - 2)
First valid address of a network = 2nd address (because first is network idenfier)
Last valid address of a network = last address - 1
