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I have noticed that some root and intermediate CAs have things like "G2" or "G3" in the name.
For example, take the certificate for amazon.com. The intermediate CA is DigiCert Global CA G2, and the root CA is DigiCert Global Root G2.
I understand that "G2" means "Generation 2." But what is the purpose of having a second-generation CA? What changed between the first and second generations?