Hosting the complete ipv6 reverse zone file

We’ve been running IPv6 for a while and one of the unresolved issues we’re having is how to handle reverse dns. For IPv4 we have a control panel which allows customers to set their reverse dns records. For IPv6 we’ve been putting individual records in or delegating the address space to the end customers DNS server. We don’t think that making all of our customers run a DNS server just to do reverse DNS is particularly desirable but there are issues in hosting several billion reverse records per customer if they happen to come up with an application that uses their entire address space.

This got me wondering, how hard would it be to host the complete IPv6 reverse zone file. It’s roughly 3.4 x 10^38 addresses. Storing this in memory for speedy lookup would be desirable. Flash is made out of silicon which is made out of sand. wiki.answers.com under ‘How many grains of sand are there in the world’ and ‘How many atoms are there in a grain of sand’ give the answers 7.5 x 10^ 18 grains of sand and 2 x 10^ 19 atoms per grain. Multiplying these together we get roughly 1.5 x 10^38 atoms in total for the whole world.

So if we take all the sand in the world and manufacture it into DRAM we need to store roughly two reverse lookups per atom to store the whole zone file. Answers on a postcard.