Allowing DNS to listen only on UDP

[Reindl Harald]

Am 21.04.2017 um 13:12 schrieb Reindl Harald:
> Am 21.04.2017 um 12:55 schrieb Harshith Mulky
>> Is there a easy way to turn off/ Disable the DNS server to stop 
>> listening the requests over TCP and turn it ON whenever required?
> 
> no and it does not make sense at all
> 
> tcp is required for:
> 
> * zone transfers
> * EDNS
> 
> if it ain't broken don't fix it

to make it clear - i was years ago taht stoopid too and opened TCP only 
for the machines doing zone transfers but we saw random resolution 
errors reported from users which ever appeared again after open port 53 
for UDP and TCP and that was long before EDNS and DNSSEC where a topic 
like these days