TCP Fast Open? Not so fast
> If the answer is too big for UDP, DNS falls back to TCP and this fall-back is used more often these days. With the emergence of DNSSEC and TXT records, large answers are more common than they used to be.<p>I did not know that was a thing!<p><a href="https://serverfault.com/questions/698251/how-does-the-dns-protocol-switch-from-udp-to-tcp" rel="nofollow">https://serverfault.com/questions/698251/how-does-the-dns-pr...</a>