An IP address (Internet Protocol address) is a unique numeric identifier assigned to every device connected to a network via the Internet Protocol. It serves as the address for identifying and routing data packets in the network, without IP addresses, no data packet would know where it’s headed.
Structure of an IP address: IPv4 vs. IPv6
| IPv4 | IPv6 | |
|---|---|---|
| Format | Four numbers separated by dots | Eight hexadecimal blocks separated by colons |
| Example | 192.168.0.1 | 2001:0db8:85a3:0000:0000:8a2e:0370:7334 |
| Address space | Around 4.3 billion addresses | Practically unlimited |
| Status | Address space exhausted for years, kept in use via NAT/CGNAT | Growing adoption, but no complete replacement of IPv4 yet |
More on the IP address’s role in the entire transmission process in the TCP/IP network entry.
Static vs. dynamic IP addresses
A static IP address is a fixed, permanent identifier that doesn’t change. It’s typically used for servers, network devices or other services that must remain reachable at the same address continuously.
A dynamic IP address, in contrast, is assigned automatically by a DHCP server (Dynamic Host Configuration Protocol) and can change over time, say, after a router restart. For most private internet connections and smaller networks, that’s the norm.
Public vs. private IP addresses
A further important distinction concerns an address’s reach:
- Public IP address: unique across the entire internet, assigned by the internet provider. This is what makes a network reachable from outside.
- Private IP address: valid only within a local network (typical ranges:
10.0.0.0/8,172.16.0.0/12,192.168.0.0/16), distributed by the router to individual devices in the home or office network.
Via NAT (network address translation), all devices in a local network usually share one common public IP address towards the outside, which is the reason the real IPv4 address shortage hasn’t led to total failure despite billions of connected devices.
IP addresses and privacy: personal data
IP addresses are no side issue in data protection law: the European Court of Justice ruled back in 2016 that dynamic IP addresses too can be personal data within the meaning of the GDPR, provided identification of the person behind them, for example via internet provider disclosure – is legally possible. In practice that affects every website storing IP addresses in log files or processing them via analytics tools like Google Analytics – a legally compliant configuration with IP anonymisation and a fitting privacy policy is accordingly mandatory, not optional.
What IP addresses are used for in practice
- Routing: the basic function, without IP addresses, data packets can’t find their destination.
- Geolocation: approximate location determination for language selection, currency display or regional content, usually at city or region level, not exact.
- Security and rate limiting: conspicuous IP addresses can be blocked or throttled – a central line of defence against DDoS attacks, for instance.
- Content delivery networks: a CDN delivers content via regionally distributed edge servers selected based on the requesting person’s IP address.
The 2026 trend: IPv6 adoption and the slow end of IPv4
The IPv4 address space has been formally exhausted for years; new address blocks are practically no longer issued by the internet registries. In day-to-day operation, NAT/CGNAT (carrier-grade NAT) nevertheless keeps IPv4 alive by letting many users share the same public address. At the same time, IPv6 adoption keeps growing noticeably, led by mobile networks, which are technically furthest along – fixed-line and above all corporate networks often lag behind in the switch, partly because of the internal migration effort. For website operators this means: IPv6 reachability now belongs to the technical basics, no longer the extras.
Practical security tips around IP addresses
- Use a VPN or proxy to hide your own IP address from destination sites.
- Define firewall rules on an IP basis to restrict or allow access in a targeted way.
- Set up rate limiting to limit automated requests from individual IP addresses.
- Handle log files in a privacy-compliant way: don’t store IP addresses longer than necessary and anonymise where possible.
Conclusion
The IP address is one of the most fundamental yet most underestimated components of network communication: technically indispensable for routing, while simultaneously a datum relevant under data protection law that must be handled correctly in log files, analytics tools and security concepts. We’re happy to support you with the secure, GDPR-compliant configuration of your infrastructure as part of our maintenance and security services or simply get in touch and we’ll take a look together.