Cheatsheet - Networking Lookup Tables
RFC 1918 Private Networks IP Address Ranges
Assigned by Internet Assigned Numbers Authority (IANA).
| Class | IP Range |
|---|---|
| Class A | 10.0.0.0 to 10.255.255.255 |
| Class B | 172.16.0.0 to 172.31.255.255 |
| Class C | 192.168.0.0 to 192.168.255.255 |
Layers and Protocols
| Layer | Name | Protocols / Usage / Devices |
|---|---|---|
| Layer 7 | Application Layer | HTTP, FTP, BGP, SNMP |
| Layer 6 | Presentation Layer | |
| Layer 5 | Session Layer | SOCKS, Gateway |
| Layer 4 | Transport Layer | TCP, UDP |
| Layer 3 | Network Layer | IP, ICMP, Layer 3 Switch |
| Layer 2 | Data Link Layer | Switch, Bridge, MAC, LLC, PPP |
| Layer 1 | Physical Layer | Hub |
Subnet masks and IP addresses
| Mask | IP addresses | Hosts | Netmask |
|---|---|---|---|
| /31 | 2 | 2 | 255.255.255.254 |
| /30 | 4 | 2 | 255.255.255.252 |
| /29 | 8 | 6 | 255.255.255.248 |
| /28 | 16 | 14 | 255.255.255.240 |
| /27 | 32 | 30 | 255.255.255.224 |
| /26 | 64 | 62 | 255.255.255.192 |
| /25 | 128 | 126 | 255.255.255.128 |
| /24 | 256 | 254 | 255.255.255.0 |
| /23 | 512 | 510 | 255.255.254.0 |
| /22 | 1024 | 1022 | 255.255.252.0 |
| /21 | 2048 | 2046 | 255.255.248.0 |
| /20 | 4096 | 4094 | 255.255.240.0 |
| /19 | 8192 | 8190 | 255.255.224.0 |
| /18 | 16384 | 16382 | 255.255.192.0 |
| /17 | 32768 | 32766 | 255.255.128.0 |
| /16 | 65536 | 65534 | 255.255.0.0 |
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