IP Address
An IP (Internet Protocol) address is a unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. IPv4 addresses are 32-bit numbers typically written in dotted-decimal notation (e.g., 192.168.1.1), providing approximately 4.3 billion unique addresses, while IPv6 addresses are 128-bit numbers written in hexadecimal (e.g., 2001:0db8:85a3::8a2e:0370:7334) to accommodate the growing number of internet-connected devices. IP addresses serve two principal functions: host or network interface identification and location addressing.
Key Formula
Total IPv4 Addresses = 2^32 = 4,294,967,296
LaTeX: \text{Total IPv4 Addresses} = 2^{32} = 4{,}294{,}967{,}296
| Symbol | Meaning | Unit |
|---|---|---|
| 2 | Binary base (each bit is 0 or 1) | none |
| 32 | Number of bits in an IPv4 address | bits |
Worked Example
Problem
Convert the IPv4 address 192.168.10.5 into binary and determine whether it belongs to a private network.
Solution
Step 1: Convert each octet to 8-bit binary. 192 = 11000000 168 = 10101000 10 = 00001010 5 = 00000101 Full binary: 11000000.10101000.00001010.00000101 Step 2: Check private ranges (RFC 1918). Private ranges: 10.0.0.0–10.255.255.255, 172.16.0.0–172.31.255.255, 192.168.0.0–192.168.255.255. 192.168.10.5 falls within 192.168.0.0/16, so it is a private IP address.
Answer
Binary: 11000000.10101000.00001010.00000101 — Private IP (192.168.x.x range)
IPv4 Address Classes
| Class | Range | Default Mask | Networks | Use |
|---|---|---|---|---|
| A | 1.0.0.0 – 126.255.255.255 | 255.0.0.0 | 126 | Large organisations |
| B | 128.0.0.0 – 191.255.255.255 | 255.255.0.0 | 16,384 | Medium organisations |
| C | 192.0.0.0 – 223.255.255.255 | 255.255.255.0 | 2,097,152 | Small networks |
| D | 224.0.0.0 – 239.255.255.255 | N/A | N/A | Multicast |
| E | 240.0.0.0 – 255.255.255.255 | N/A | N/A | Reserved/Research |
Interactive Tools
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Related Terms
DNS (Domain Name System)
The Domain Name System (DNS) is a hierarchical, distributed naming system that translates human-readable domain names (such as www.google.com) into numerical IP addresses (such as 142.250.195.68) that computers use to communicate. Often described as the "phone book of the internet," DNS makes it possible for users to access websites using memorable names instead of numeric addresses. DNS queries are typically resolved through a chain of DNS servers including recursive resolvers, root servers, TLD servers, and authoritative name servers.
Subnet Mask
A subnet mask is a 32-bit number used in conjunction with an IP address to divide a network into smaller sub-networks (subnets) by identifying which bits of the IP address represent the network portion and which represent the host portion. Written in dotted-decimal notation (e.g., 255.255.255.0) or CIDR notation (e.g., /24), it enables routers and devices to determine whether a destination address is on the local network or must be forwarded to another network. Subnetting improves network performance, security, and efficient use of IP address space.
TCP/IP Protocol
TCP/IP (Transmission Control Protocol/Internet Protocol) is the foundational suite of communication protocols used to interconnect network devices on the internet and most private networks. TCP handles reliable, ordered delivery of data by breaking messages into packets, acknowledging receipt, and retransmitting lost segments, while IP handles addressing and routing each packet to its destination. Together they form the backbone of modern digital communication, enabling everything from web browsing to email.
The term "Internet Protocol" was formalised in RFC 791 by Jon Postel in 1981. "Internet" derives from Latin inter (between) + network, originally short for "internetwork." "Protocol" comes from Greek protokollon. The dotted-decimal notation was introduced to make 32-bit binary numbers human-readable.