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@case.edu> Date: Thursday 2021-01-28 at 17:01 To: Hugo Salgado <hsalgado@nic.cl> Cc: RIPE Atlas <ripe-atlas@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@nic.cl<mailto:hsalgado@nic.cl>> 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

That makes sense. Thanks! Regards, Grzegorz From: Hugo Salgado <hsalgado@nic.cl> Date: Thursday 2021-02-04 at 16:40 To: "Ponikierski, Grzegorz" <gponikie@akamai.com> Cc: Michael Rabinovich <michael.rabinovich@case.edu>, RIPE Atlas <ripe-atlas@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@case.edu<mailto:michael.rabinovich@case.edu>> Date: Thursday 2021-01-28 at 17:01 To: Hugo Salgado <hsalgado@nic.cl<mailto:hsalgado@nic.cl>> Cc: RIPE Atlas <ripe-atlas@ripe.net<mailto:ripe-atlas@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@nic.cl<mailto:hsalgado@nic.cl><mailto:hsalgado@nic.cl><mailto:hsalgado@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