how to identify dns server that can support tcp conn reuse?

[Nyx2022]

hello ,i found this lib is complex with some dns protocols supported,and i wanna use dns over tcp,i found you use pipeline to speedup,but it has a err in https://github.com/folbricht/routedns/blob/master/pipeline.go. line 145,when the err is eof,o the conn must be closed, which means that the dns server can not support send multi dns query in one tcp connection, so i wanna know how can i detect some dns server if support send multi dns query in one tcp connection,or is there any method to let dns server know that i wanna send multi dns query in one tcp connection.

[folbricht]

Can you describe what isn't working as expected. I'm pretty sure pipelining allows sending multiple queries through a single connection. Are you having issues with some TCP server that doesn't allow it and closes the connection? You can run routedns -l6 ... to enable full logging and I believe that would show when servers close the connections.

[Nyx2022]

ok,thank you ,i think your lib is very well,my need is wanna identify dns server if support sending multiple queries through a single tcp connection,if not ,i will not use it again,except by -16 to test many queries,is there any other methods by check some flag in response?

[folbricht]

I don't know of a way to easily identify TCP DNS servers that don't support connection-reuse. On the other hand, I haven't seen one that doesn't allow multiple queries to be sent over a single connection. Are you sure that's a problem you're having?

[Nyx2022]

yes ,perhaps it's my mistake ,i'll wend here when i gotten the bad dns server

[cbuijs]

I think most of the encrypted DNS protocols that use TCP allow "streaming" or keep the connection open to do multiple requests over the same connection? It does not always work, but should work.