HTTP & Networking
What is IPv6?
The successor to IPv4, using 128-bit addresses to provide a vastly larger address space and a few protocol simplifications.
IPv6 was designed in the 1990s once it became clear IPv4 would run out of addresses. A v6 address looks like 2001:0db8:85a3:0000:0000:8a2e:0370:7334, which collapses with double-colon shorthand to 2001:db8:85a3::8a2e:370:7334. The address space is 2^128, enough to assign trillions of addresses per square millimeter of Earth.
Beyond size, IPv6 cleans up several IPv4 quirks. There is no NAT in the v6 model: every device gets a globally routable address. Header processing is simpler and fragmentation is handled by the sender rather than routers. Stateless address autoconfiguration (SLAAC) lets devices generate their own addresses from a router prefix without a DHCP server.
Adoption is uneven. Mobile networks in the US and India are mostly v6; many enterprise and small-business networks are still v4-only. For crawlers, the practical impact is that a v6-only target requires v6-capable proxies, and IP-based rate limiting on v6 has to be by /64 prefix rather than per address (since one device can trivially rotate within its /64).
In the wild
- →A T-Mobile phone connecting to youtube.com over IPv6 with a v4 fallback for legacy services
- →A data center scraper using a /64 prefix to rotate IPs without buying a new proxy
- →A geolocation database tagging a /48 v6 prefix with a city since v6 is allocated more granularly than v4
How Brand.dev uses ipv6
Endpoints in the Brand.dev API where this concept comes up directly.
FAQ
Why has IPv6 adoption taken so long?
IPv4 + NAT works "well enough" for most users, and migration costs are non-trivial: every router, firewall, and monitoring tool has to understand v6. Adoption is closer to 45% of Google traffic now and rising.
Do I need IPv6 for my service?
Not strictly: dual-stack v4+v6 covers everyone. But v6 latency is sometimes lower on mobile networks because it avoids carrier-grade NAT.
How do I rate-limit IPv6 traffic?
Per /64 prefix, not per address. A single subscriber typically gets a /64 (or /48), so per-address limits are trivial to evade.
Related terms
A numeric label assigned to every device on a network that uses the Internet Protocol, used to route packets between hosts.
The Domain Name System, the distributed database that translates human-readable domain names into the IP addresses computers actually route to.
Transmission Control Protocol, a reliable, ordered, connection-oriented transport that sits below HTTP and most other application protocols.
The application protocol the web is built on, a simple request/response format for asking a server for a resource.