Lets assume I have a tumblr account:
Tumblr allows it so that it can point to www.sheehan.com if I enter an A-Record.
How does Tumblr scale this to millions of users? How is it possible to assign a single A-Record to multiple subdomains?
Lets assume I have a tumblr account:
Tumblr allows it so that it can point to www.sheehan.com if I enter an A-Record.
How does Tumblr scale this to millions of users? How is it possible to assign a single A-Record to multiple subdomains?
basically there is an apache/whatever header directive that redirects it to your site. It will be a very small amount of data ( check out 301/ moved permanently headers for more ).
For scaling it to millions, this kind of data ( username (key) -> custom domain(value) ) you could store the data for all the users in a memory mapped hash and then put a squid ( or similar ) proxy to cache.