I repeated my search just now and got the following list of sources: - https://www.arc-it.net/html/standards/standard1117.html https://www.arc-it.net/html/stan

I repeated my search just now and got the following list of sources: - https://www.arc-it.net/html/standards/standard1117.html https://www.arc-it.net/html/standards/standard1117.html - https://www.youtube.com/watch?v=_WH1Z8htjMo https://www.youtube.com/watch?v=_WH1Z8htjMo - https://www.youtube.com/watch?v=7cG-GDpMA4k https://www.youtube.com/watch?v=7cG-GDpMA4k - https://www.tech-invite.com/y05/tinv-ietf-rfc-0793.html https://www.tech-invite.com/y05/tinv-ietf-rfc-0793.html - https://www.maths.tcd.ie/~eoin/index/isi_793rfc81.html https://www.maths.tcd.ie/~eoin/index/isi_793rfc81.html This list is different from my previous search yesterday, so I don't doubt that in your case you got different sources than me. It does look like the sources include mirrors of the RFC hosted by arc-it.net and tech-invite.com. I do not recognize these domains and would much prefer to see an ietf.org domain instead (which is also the first Google result in my case).