[atlas] querying the config

That makes sense. Thanks!

Regards,
Grzegorz

From: Hugo Salgado <hsalgado at nic.cl>
Date: Thursday 2021-02-04 at 16:40
To: "Ponikierski, Grzegorz" <gponikie at akamai.com>
Cc: Michael Rabinovich <michael.rabinovich at case.edu>, RIPE Atlas <ripe-atlas at ripe.net>
Subject: Re: [atlas] querying the config

Hi Grzegorz. As far as I know, the dst_addr have the destination IP
address of the packet that the probe sent for a DNS measurement. So
if used the "use_probe_resolver:true" setting, it should be the
"frontend" resolver in your characterization. One of the resolvers
configured in probe's /etc/resolv.conf.

Regards,

Hugo

On 10:51 03/02, Ponikierski, Grzegorz wrote:
It's important to notice that whoami.ds.akahelp.net will give you backend IP of resolver (IP used to communicate with authoritative name server). If somebody needs frontend IP then this query won't help.

Hugo or Robert, can you tell which IP (frontend or backend) we will get from dst_addr field?

Regards,
Grzegorz

From: Michael Rabinovich <michael.rabinovich at case.edu<mailto:michael.rabinovich at case.edu>>
Date: Thursday 2021-01-28 at 17:01
To: Hugo Salgado <hsalgado at nic.cl<mailto:hsalgado at nic.cl>>
Cc: RIPE Atlas <ripe-atlas at ripe.net<mailto:ripe-atlas at ripe.net>>
Subject: Re: [atlas] querying the config

Hi Randy,

In addition, whether it's the configuration or the IP address used by the probe for a query as Hugo suggested, this would only give you the entry point into the resolution path (and sometimes will be a private IP address of a simple forwarder).  But you can query for TXT record for whoami.ds.akahelp.net, which will return you the IP address of the egress resolver.

Misha


On Jan 27, 2021, at 4:03 PM, Hugo Salgado <hsalgado at nic.cl<mailto:hsalgado at nic.cl><mailto:hsalgado at nic.cl><mailto:hsalgado at nic.cl%3e>> wrote:

Hi Randy. I don't know if you can check the config, but if you launch
a DNS measurement taking care to define use_probe_resolver:true, then
in the dst_addr field of the results you will have the IP that it used
as the resolver.

Hugo

On 12:23 27/01, Randy Bush wrote:
howdy

so i wanted info about a probe's config, specifically what dns
resolver(s) it is using.  i could not figure out how to do this.
assuming it was a lack of clueons, i asked a friend with far deeper
atlas fu.  they said such queries are not available.  really?

[ yes we have bright ideas on how to discover this indirectly by
   mining past data ]

but really?

randy





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