Ravi Sir's Cards › AWS
What is a CORS preflight?
What is a VPC: your own private network inside one AWS Region, example ThreeTierVpc 10.0.0.0/16.
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What this card says
What it is
Browser OPTIONS request before some cross-origin calls.
Why it matters
Server must answer Allow-Methods and Allow-Headers.
How / example
If OPTIONS fails, the real POST never leaves the browser.