Exact semantics of DNS' use_probe_resolver
The DNS-specific option use_probe_resolver is mentioned in <https://atlas.ripe.net/docs/measurement-creation-api/> but with little indication of the semantics. My experience is that some probes (with the default retry=0) return several responses, with the same "prb_id", but different "from". I assume it means the probe had several resolvers configured and tried them all. Am I correct? It may question some conclusions of <https://labs.ripe.net/Members/stephane_bortzmeyer/how-many-ripe-atlas-probes-can-resolve-ipv6-only-domain-names>. Is there an option to switch to the more typical behaviour of a DNS client (try the first resolver configured and switch to the second if the first does not reply)?
Hi Stephane, On 2015/03/15 22:18 , Stephane Bortzmeyer wrote:
The DNS-specific option use_probe_resolver is mentioned in <https://atlas.ripe.net/docs/measurement-creation-api/> but with little indication of the semantics.
My experience is that some probes (with the default retry=0) return several responses, with the same "prb_id", but different "from". I assume it means the probe had several resolvers configured and tried them all.
The semantics of 'use_probe_resolver' is that the probe will send a DNS query to all resolvers listed in /etc/resolv.conf that match the particular IP version of the measurement. I assume that if you want just one result, you can extract that during processing the results. Philip
On Mon, Mar 16, 2015 at 12:11:26PM +0100, Philip Homburg <philip.homburg@ripe.net> wrote a message of 20 lines which said:
I assume that if you want just one result, you can extract that during processing the results.
OK, implemented in 9091fc624345fc9cddf6f2070dca1f51a27fbac2 <https://github.com/RIPE-Atlas-Community/ripe-atlas-community-contrib/commit/9091fc624345fc9cddf6f2070dca1f51a27fbac2>
participants (2)
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Philip Homburg -
Stephane Bortzmeyer