The key differences between IPv4 and IPv6
The headline difference is size: IPv4's 32-bit space tops out at ~4.3 billion addresses, which the internet ran out of years ago, while IPv6's 128-bit space is effectively limitless. That scarcity is why IPv4 leans heavily on NAT (many devices sharing one public address), whereas IPv6 can give every device a unique public address. The notation differs too — IPv4 is four dotted decimal octets, IPv6 is eight hex groups separated by colons (with
:: shorthand for runs of zeros). IPv6 also simplified the packet header and builds in features (like stateless autoconfiguration and mandatory support for IPsec) that were bolt-ons in IPv4.Why IPv6 exists
IPv6 was created specifically to solve IPv4 address exhaustion. As billions of phones, servers, and IoT devices came online, the 4.3-billion IPv4 ceiling became a hard limit, kept alive only by NAT and a secondary market for IPv4 blocks. IPv6's enormous space removes that constraint. Adoption is gradual because the two protocols aren't directly interoperable — the internet runs both in parallel (dual-stack) during the long transition, so most networks still need working IPv4 alongside IPv6.
IPv4 vs IPv6 for proxies and web scraping
For scraping, the practical question isn't which protocol is 'better' — it's which one your targets trust. Many sites and anti-bot vendors still treat IPv4 residential addresses as the most human-looking, while large blocks of IPv6 (a single ISP can hand out a whole /64) are easier to fingerprint and ban in bulk, so suspicious IPv6 ranges get blocked wholesale. Datacenter IPv6 in particular is often distrusted. The upshot: for protected targets, residential proxies on IPv4 are usually the most reliable choice, while IPv6 can be fine for IPv6-only sites or high-volume, low-sensitivity crawling. If you're seeing blocks correlated with IP version, switching to trusted IPv4 residential addresses is the first thing to try.