named tcp dos?

Randy Bush randy at
Thu Aug 2 20:27:16 UTC 2018

>> estimate or measure the distribution of the ratio of udp to tcp
>> queries on say 100 cctld servers
> bla - 512 bytes are easily exceeded
> more than 10 years ago i also thought i am smart and TCP 53 is only
> needed for zone-transfers until i realized that random e-mail errors
> where the result of large TXT records including way too verbose SPF
> open TCP 53 for the world and all problems where gone forever

in my case, tcp was open and that is where the problem arose :)

i am trying to tune per daniel's

> Depending on your "max-udp-size" value (default 4096) you may also
> want to increase "tcp-clients" setting (default 150).

and am trying to understand the space


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