client retry logic on TCP/TLS connection closure
When remote server closes a connection without answering a part of our queries, the corresponding requests get failed too aggressively (perhaps? TODO: details, etc.)
Most interesting parts of standards is 7766:
DNS clients SHOULD retry unanswered queries if the connection closes before receiving all outstanding responses.
On the other hand servers SHOULD not close the connections early, without reasons for the particular case... so hopefully this won't happen that often in practice; FRITZ! seems a notable case. I'll keep copying the important points from that discussion to here.