Leading Web content providers -- including Google, Yahoo, Netflix and Microsoft -- are conducting early-stage conversations about creating a shared list of customers who can access their Web sites via IPv6, the long-anticipated upgrade to the Internet's main communications protocol.
The DNS Whitelist for IPv6 would be a list of IP addresses that have functioning IPv6 connectivity. Content providers would use this shared DNS Whitelist to serve up content to these IP addresses via IPv6 rather than through IPv4, which is the current version of the Internet Protocol. Web site visitors not listed on the DNS Whitelist for IPv6 would receive IPv4-based content.
The shared DNS Whitelist for IPv6 is a controversial proposal, with content providers saying it is the only viable option for offering IPv6 services today, and ISPs worrying that maintaining the whitelist will be an administrative burden in the future.
The idea of creating a shared DNS Whitelist for IPv6 was discussed at the Internet Engineering Task Force (IETF) meeting held here this week. The IETF is the standards body responsible for IPv6 and IPv4.
The Internet infrastructure is migrating to IPv6 because it is running out of IPv4 addresses. IPv4 uses 32-bit addresses and can support 4.3 billion devices connected directly to the Internet. IPv6, on the other hand, uses 128-bit addresses and supports a virtually unlimited number of devices.
Experts predict that the remaining IPv4 addresses will be distributed by 2012. In January, the Regional Internet Registries announced that fewer than 10% of IPv4 addresses remain unallocated.
When IPv4 addresses run out, carriers and enterprises must support IPv6 in order to add new customers and devices to their networks. Otherwise, network operators will need complex and expensive layers of network address translation (NAT) to share scarce IPv4 addresses among multiple users and devices.
IPv6 requires changes to the Internet's Domain Name System, which matches IP addresses and their corresponding domain names. The DNS uses single A records for IPv4-based queries, but it uses quad-A records for IPv6 queries. The DNS Whitelist for IPv6 would be used by content providers to pass quad-A records upstream to ISPs only if the user's DNS resolver is in the whitelist.
Content providers say they need a DNS Whitelist for IPv6 because the Internet has so many broken IPv6 links due to problematic default behavior and incompatibilities in operating systems, home gateways and customer premises equipment. Without a whitelist to help sort out which customers can and cannot receive IPv6 content, Web developers say they will inadvertently block too many customers from accessing their content.
For example, Google has its own DNS Whitelist for its IPv6 services, which include YouTube, Search, Docs, Gmail, News and Maps. Google has said that the DNS Whitelist for IPV6 was the easiest way it could provide IPv6 services without blocking customers with broken IPv6 links.