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who keeps that data locally on the server?

Anyone implementing business-critical applications which have to continue to function if external services go down.

Ever wondered how cash registers work? Exactly like that. The world may burn down around you, but as long as your cash register PC is running, it must continue to at least offer basic functionality.

You mean like all of the cash registers at companies like Target that were breached because they were distributed?

https://www.post-gazette.com/business/2013/12/19/Target-ackn...

The vast majority of point of sale systems are networked, and this is nothing new. There's literally millions of PoS systems out there running off of AS/400 backends, even today.

If you're querying the IRS for tax rates every time you run a calculation, you're doing it wrong.

If you aren’t querying exchange rates often - you’re also doing it wrong....

Depends on what you're using the exchange rates for. The rates used by Visa only change once per day, as an example.

And you still wouldn’t store that locally. You may cache it locally - something you could also practically do with lambda.

Well yes, the parent we're replying to was talking about caching.

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