What is the best approach for developing an appointment system on web with asp.net mvc for 70 millions of people?

I will develop an appo开发者_C百科intment application with asp.net mvc? This application will be used by 70 M people. And at least 30000 - 40000 user will log on to the system at the same time. What is the best approach for developing this kind of intense application with asp.net mvc and sql server? Can you please share your opinions about this?

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Make your sql-routines as efficient as possible, select more data than you need and cache it on the web-server, only to invalidate when there is actually any new content. Cache the pages through IIS and retrieve critical non-cacheable data through cache substitution. Invest in a bunch of really big servers! :)

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Contract out the design, development and hosting to a team or company who have done it before. (Or something similar to it...)

The StackOverflow team for example, have done something roughly similar to this... but possibly not at that level yet.