hey zirias, thank you for your answer.
as far as syn cookies goes, I think it has been developed independently of syn cache. Even in the RFC you refer to, there is a solid distinguishment between those two. In the early years of the development of SYN Cookie, I think they have been used simultaneously in order to improve the efficiency of the SYN flood mitigations techniques. In simpler words, as soon as the hash-table of the SYN Cache was about to fill up, the SYN Cookie was triggered. Nowadays, I think there is only SYN Cookie in use,or, I have not come across a relevant reference yet.
If any of you knows where I can find any information about this issue, please let me know. I will be more than grateful for your help.
Thank you one more time for all your resources used up accordingly