[atlas] Support for arbitrary DNS queries

On 24/12/15 10:59, Gil Bahat wrote:

Dear Gil,

> Unfortunately, this doesn't seem to work so well either:
> https://atlas.ripe.net/measurements/3115499/
> Can anyone here help me figure out why almost all requests end up being
> null and only very few of them show up the resultant TXT record?

The OARC reply-size tester works by sending a recursive resolver a
series of CNAME records to follow. If the resolver has no problems, then
it follows the chain quickly, and gets a result. However, if there are
path MTU issues, for example, these queries time out. In this case, a
resolver will take a long time to come back with the result.

The RIPE Atlas DNS measurements all time out after 5 seconds, and this
isn't enough time to always get results from the reply-size tester. This
is most likely the reason why most of your results are empty, with a
"timeout" error.

Regards,
Anand