IPv4 vs IPv6

IPv4 uses 32-bit addresses in the format 203.0.113.42 — the global address pool has been exhausted since 2011, free IPv4 blocks trade on secondary markets for $40–60 per address. Hosting providers therefore often price IPv4 separately per cloud instance (Hetzner Cloud: ~€0.60/month) or skip it by default (AWS Lightsail). IPv6 (128 bit, 2001:db8::1) has been standardised since 1998 and solves the address problem long-term but is only actively used by ~45 % of internet users — meaning a pure IPv6-only server is unreachable for many visitors and older mail servers. Best practice: dual-stack setup with IPv4 + IPv6, fallback configured. Hosting check: IPv6 is included by all reputable European hosts (netcup, Hetzner, Cloud86, 1blu), IPv4 increasingly priced separately.