Networking
IPv6
IPv4's successor — 128-bit addresses providing enough unique IPs for every device on earth. Written as eight groups of hex digits separated by colons.
IPv6 is the successor to IPv4, using 128-bit addresses to provide a vastly larger address space — enough for every device on earth to have a unique public IP. IPv6 addresses are written as eight groups of four hexadecimal digits separated by colons.
IPv4's 4.3 billion address limit was always going to run out. IPv6 replaces the 32-bit address with 128 bits, producing 340 undecillion addresses — a number large enough that address exhaustion is no longer a practical concern.
An IPv6 address looks like 2001:0db8:85a3:0000:0000:8a2e:0370:7334, often shortened by omitting leading zeros and replacing consecutive groups of zeros with ::.
Key differences from IPv4:
No NAT required — every device can have a globally routable public address. The privacy implications are handled by temporary addresses and privacy extensions.
Stateless Address Autoconfiguration (SLAAC) — devices can configure their own IPv6 addresses from the network prefix without a DHCP server, though DHCPv6 also exists.
Built-in IPsec — IPv6 was designed with security in mind, though in practice this is less significant than the marketing suggested.
No broadcast — IPv6 uses multicast and anycast instead, reducing unnecessary traffic.
Despite being standardized in 1998, IPv6 adoption in enterprise networks has been slow. Most SMB and mid-market organizations still run IPv4-only internally, relying on ISPs and CDNs to handle IPv6 externally. Modern operating systems, cloud providers, and ISPs are all dual-stack, meaning the transition is ongoing rather than complete. If you're designing a new network today, supporting dual-stack is worth planning for even if IPv6 isn't a day-one priority.