IP Address

What is an IP Address?

IP Address stands for Internet Protocol Address. It is a unique number assigned to every device on a network—like a mailing address for computers. More precisely, the address belongs to an individual network interface. A device with multiple network connections, such as Wi-Fi and Ethernet at the same time, can therefore have multiple IP addresses simultaneously.

How it works

When your computer accesses dragons-at-work.de, it must know where that server is located. The IP address tells it.

• People use: dragons-at-work.de (easy to remember)
• Computers use: 95.217.163.246 (numeric address)
• DNS translates: Domain names into IP addresses

IPv4 vs. IPv6

IPv4

Format: 192.168.1.1 (four numbers from 0 to 255)

Problem: Only about 4.3 billion unique addresses are available, and the global pool was exhausted in 2011.

IPv6 (modern)

Format: 2a01:4f8:c17:b8ea::1 (hexadecimal)

Solution: Approximately 340 undecillion addresses—enough to assign millions of IP addresses to every grain of sand on Earth.

Public vs. Private

Public IP: Unique on the Internet (assigned by your Internet provider)

Private IP: Valid only within your local network

• 192.168.x.x (home networks)
• 10.x.x.x (large private networks)
• 172.16.x.x to 172.31.x.x (medium-sized private networks, such as businesses)

A router translates between private and public addresses using NAT (Network Address Translation).

Special addresses

• 127.0.0.1 — Localhost (your own computer)
• 192.168.1.1 — Common router address
• 8.8.8.8 — Google Public DNS

Static vs. Dynamic

Static: Configured manually and does not change (for example, servers or printers)
Dynamic: Assigned automatically by DHCP and may change over time (for example, laptops or smartphones)