The verification code appears when submitted multiple times (3 times)???

1 No graphic verification code will appear for the first three submissions
2 After three times, the graphic verification code will appear for verification before submission can be submitted

What is the basis for counting the number of submissions? IP? Cookie? Session? Or other ideas
If it is a SMS verification code channel and others use a dynamic IP library to attack, how to control it?

http://m.rong360.com/detail/2679?loan_limit=&loan_term=&repayment_type=0&guarantee_type=0&px=0&org_type=0

Submit like this page

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1 No graphic verification code will appear for the first three submissions
2 After three times, the graphic verification code will appear for verification before submission can be submitted

What is the basis for counting the number of submissions? IP? Cookie? Session? Or other ideas
If it is a SMS verification code channel and others use a dynamic IP library to attack, how to control it?

http://m.rong360.com/detail/2679?loan_limit=&loan_term=&repayment_type=0&guarantee_type=0&px=0&org_type=0

Submit like this page

can be processed using middleware caches such as memcache or redis, and uses IP plus cookies to control malicious requests,

Make a cache, memcache and redis. If you don’t have either, use cookies.
Our company’s anti-hotlink IP prohibits double verification of the front-end and back-end verification codes multiple times, and also adds a randomly generated token. . .