[atlas] DNS measurement using the Probe's resolvers

On Fri, Jul 06, 2018 at 04:30:11PM -0400,
 Rami Al-Dalky <rxa271 at case.edu> wrote 
 a message of 27 lines which said:

> I have a question about using the probe's list of resolvers when
> creating a DNS measurement. It is unclear to me whether the probe
> would send the query to all resolvers at the same time or not!

By default, to all resolvers. Look at measurement #15260120, for
instance. Probe 25020 used three resolvers, 2001:730:3e42:1000::53,
192.168.178.1, and 2001:730:3e42::53, and you can see the results for
all three. On the other hand, probe 17929 has just one resolver,
8.8.8.8, so you see only one object in the resultset array.

With blaeu, you can display results for all the resolvers or only for
the first one:

% blaeu-resolve -r 10 --measurement-ID=15260120   atlas.ripe.net                    
[2001:67c:2e8:22::c100:69e] : 10 occurrences 
Test #15260120 done at 2018-07-17T16:55:55Z

% blaeu-resolve -r 10 --measurement-ID=15260120 --severalperprobe  atlas.ripe.net 
[2001:67c:2e8:22::c100:69e] : 17 occurrences 
[NETWORK PROBLEM WITH RESOLVER] : 1 occurrences 
Test #15260120 done at 2018-07-17T16:55:55Z

(More results in the second case, since some probes have more than one resolver.)

> Is DNS eyeball implemented in the probes?

I don't know.