I used to work for a company which claimed to have the largest website in the world, in terms of dollars transacted per day.
The number of hits on the website was pretty low, though. Ok, so we may have traded several million dollars in a single transaction, but it only took a few of those transaction to start racking up the turnover figures. And reliability was obviously important, but not mission-critical, because our counterparties could phone us if the website went down. (Our disaster recovery procedures in the London office included disabling all of the UK-based products on the (US-based) website, and asking our counterparties to pick up the phone while we resolved some technical difficulties.)
If you want examples of high-reliability high-traffic websites, I suggest you look at sites such as Yahoo. Can't remember the last time I couldn't access Yahoo. It's traffic levels are far higher than the AIS pages, and it has a much larger database.
FFF
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