Paypal IPN notification

Are there times that Paypal IPN notifications fails? Does it work 100%?

I have problem right now.. Most of the time it works but I just now, it stop working for now reason.

I need it to work 100% so that I can add a rec开发者_JS百科ord on my database about the transaction. And know if it fails or not.

Does anyone has the same experience?

Always paypal will return the IPN. But some occasions it might delay for even days. So we cant't rely on IPN 100%. So better way to do it will be to use both IPN and PDT together. If the data is not updated using IPN we can check it an use PDT to update our database.