[dns-operations] Always replying to UDP requests with TC=1, good practice or not

[Rick Jones]

On 10/18/2015 09:39 AM, Mukund Sivaraman wrote:
> On Sun, Oct 18, 2015 at 10:02:12PM +0530, Mukund Sivaraman wrote:
>>> Is it a good idea?
>>
>> No, I don't think so. There is lot of talk these days suggesting
>> directly using TCP for DNS due to all the issues UDP has.
>
> BTW, note that replying with TC=1 triples RTT over UDP as a resolver
> today will first try UDP (1 roundtrip), then noticing TC=1, retry with
> TCP (+2 for first data).

Without coming out either in favor or opposed, I will point-out there 
exists (in Linux at least) TCP FastOpen these days which would allow the 
TCP-based query to be one RTT - after the first "traditional" exchange 
including the fast open option.

rick jones