[dns-operations] How DNS work

[Stephane Bortzmeyer]

On Mon, Nov 09, 2020 at 11:15:12AM +0700,
 Hoan Vu <vuhoan3108 at gmail.com> wrote 
 a message of 122 lines which said:

> And we have already do lab, and then the DNS Cache work out of
> order, the DNS Root is choiced rondomly.

As explained in the APNIC article, it depends on the resolver. BIND,
Knot, Unbound and the others do not use the same algorithm.

> the nature of the rule to choose the DNS Root of Resolver, what
> factor, algorithm, ....

Sometimes, it is more or less documented, but you'll probably have to
read the source code and, as you did, experiment in the lab to find out.

> Our final taget to want to know can we control the operation of the
> DNS Cache. Suppose that we have one Root Secondary Node of Anycast
> in our country (example DNS Root K), and we want to direct query of
> the DNS Cache to the that DNS Root, how can we interfere the resolve
> process to do that

Well, if it is free software (like PowerDNS, Unbound, BIND, etc), you
have to modify the source code (not for the faint of heart).