IPv4 Addresses
Comprehensive IPv4 addressing fundamentals, subnetting calculators, and reference tables for networking.
About IP Addresses
IP (Internet Protocol) addresses are unique numerical identifiers assigned to devices on a network to enable communication.
- IPv4 addresses are 32-bit numbers written in dotted decimal notation (e.g., 192.168.1.1)
- Divided into network and host portions using subnet masks
- Essential for routing, addressing, and network segmentation
IPv4 Ranges
| Class | Range | CIDR | Addresses | Purpose |
|---|---|---|---|---|
| Class A | 0.0.0.0 - 127.255.255.255 | /8 | 16,777,216 | Large Networks |
| 10.0.0.0 - 10.255.255.255 | /8 | 16,777,216 | Private networks (RFC 1918) | |
| 127.0.0.0 - 127.255.255.255 | /8 | 16,777,216 | Loopback addresses | |
| Class B | 128.0.0.0 - 191.255.255.255 | /16 | 65,536 | Medium Networks |
| 169.254.0.0 - 169.254.255.255 | /16 | 65,536 | Link-local (APIPA) | |
| 172.16.0.0 - 172.31.255.255 | /12 | 1,048,576 | Private networks (RFC 1918) | |
| Class C | 192.0.0.0 - 223.255.255.255 | /24 | 256 | Small Networks |
| 192.168.0.0 - 192.168.255.255 | /16 | 65,536 | Private networks (RFC 1918) | |
| Class D | 224.0.0.0 - 239.255.255.255 | N/A | 268,435,456 | Multicast addresses |
| Class E | 240.0.0.0 - 255.255.255.255 | N/A | 268,435,456 | Reserved/Experimental |
IPv4 Address Structure
Decimal Notation
Human-readable format (0-255 per octet)
Binary Representation
11000000.10101000.00000001.0000100132 bits total (4 octets x 8 bits each)
IPv4 Networking
Enter Address with CIDR
Network Bits:24Host Bits:8Binary Mask:11111111.11111111.11111111.00000000Subnet Mask:255.255.255.0
Key Concepts
- 32-bit address system - Four octets (8 bits each)
- CIDR notation - Classless Internet Domain Routing
- Network and Host portions - Determined by subnet mask
- Reserved addresses - Network and broadcast addresses
Network Details
Network Address:192.168.1.0First Usable Host:192.168.1.1Last Usable Host:192.168.1.254Broadcast Address:192.168.1.255Subnet Mask:255.255.255.0Total Addresses:256Usable Hosts:254
Host Calculation
Hosts = 2^(32-24) - 2
Hosts = 2^8 - 2
Hosts = 256 - 2
Hosts = 254CIDR Subnet Reference Table
| CIDR | Subnet Mask | Binary Mask | Hosts | Networks | Class |
|---|---|---|---|---|---|
| /8 | 255.0.0.0 | 11111111.00000000.00000000.00000000 | 16,777,214 | 256 | A |
| /16 | 255.255.0.0 | 11111111.11111111.00000000.00000000 | 65,534 | 65,536 | B |
| /24 | 255.255.255.0 | 11111111.11111111.11111111.00000000 | 254 | 16,777,216 | C |
| /25 | 255.255.255.128 | 11111111.11111111.11111111.10000000 | 126 | 33,554,432 | - |
| /26 | 255.255.255.192 | 11111111.11111111.11111111.11000000 | 62 | 67,108,864 | - |
| /27 | 255.255.255.224 | 11111111.11111111.11111111.11100000 | 30 | 134,217,728 | - |
| /28 | 255.255.255.240 | 11111111.11111111.11111111.11110000 | 14 | 268,435,456 | - |
| /29 | 255.255.255.248 | 11111111.11111111.11111111.11111000 | 6 | 536,870,912 | - |
| /30 | 255.255.255.252 | 11111111.11111111.11111111.11111100 | 2 | 1,073,741,824 | Point-to-Point |
| /31 | 255.255.255.254 | 11111111.11111111.11111111.11111110 | 2 | 2,147,483,648 | Point-to-Point |
| /32 | 255.255.255.255 | 11111111.11111111.11111111.11111111 | 1 | 4,294,967,296 | Host Route |