Knowledge
IPv4 vs IPv6
Why the internet is transitioning to a new protocol
IPv4
Introduced1981
Address length32 bits
Format203.0.113.42
Total addresses~4.3 billion
StatusExhausted since 2011
NAT requiredYes
IPSecOptional
Header size20-60 bytes
IPv6
Introduced1998
Address length128 bits
Format2001:db8::1
Total addresses340 undecillion
StatusGrowing adoption
NAT requiredNo
IPSecBuilt-in
Header size40 bytes (fixed)
Key differences at a glance
FeatureIPv4IPv6
Address space4.3 billion340 undecillion
Address notation192.168.1.12001:db8::1
NATRequiredNot needed
Auto-configurationDHCP onlySLAAC + DHCPv6
SecurityOptional (IPSec)Built-in (IPSec)
BroadcastYesNo (multicast)
Header complexityVariableFixed (simpler)
DNS recordAAAAA
Why is IPv6 adoption slow?

Despite IPv4 exhaustion, the transition to IPv6 has been gradual. NAT (Network Address Translation) allowed many devices to share a single IPv4 address, delaying the urgency. Additionally, IPv6 requires updates to routers, ISP infrastructure and software. However, major ISPs and tech companies are now actively rolling out IPv6 – Germany has one of the highest IPv6 adoption rates in the world at over 60%.

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IPv4 and IPv6 – two generations of the internet protocol

IPv4 has been the backbone of the internet since 1981 but its 4.3 billion addresses ran out in 2011. IPv6, with its 128-bit addresses and virtually unlimited address space, is the solution. Beyond address space, IPv6 offers built-in security, simplified headers and automatic address configuration. The transition is ongoing – most modern devices and networks support both protocols simultaneously (dual-stack).