[atlas] Using Atlas for Monitoring of Anycast DNS

We make pretty extensive use of Sagan for most of our Atlas analysis. It's
maybe a little less critical for our DNS measurements (as compared to say
traceroutes, where interpreting things like error conditions can be
convoluted), especially since, as mentioned, you can often get DNS
responses to encode everything you want (i.e. NSID or hostname.bind chaos
queries).

-Marcel

On Thu, Jan 16, 2020 at 7:45 AM Stephane Bortzmeyer <bortzmeyer at nic.fr>
wrote:

> On Thu, Jan 16, 2020 at 04:33:47PM +0100,
>  Klaus Darilion <klaus.mailinglists at pernau.at> wrote
>  a message of 48 lines which said:
>
> > - analyze the probe locations (ie. country, continent)
>
> Instead of analyzing it afterwards, why not directly asking probes on
> the place you're interested in?
>
> I often use NSID to watch anycast servers, indeed:
>
> % blaeu-resolve --requested 100 --area West --nameserver $(dig +short
> +nodnssec d.nic.fr A) --type SOA --nsid --displayrtt fr
> Nameserver 194.0.9.1
> [NSID: b'dns.th2.nic.fr' nsmaster.nic.fr. hostmaster.nic.fr. 2225269298
> 3600 1800 3600000 5400] : 34 occurrences Average RTT 146 ms
> [NSID: b'dns.fra.nic.fr' nsmaster.nic.fr. hostmaster.nic.fr. 2225269298
> 3600 1800 3600000 5400] : 3 occurrences Average RTT 100 ms
> [NSID: b'dns.nyc.nic.fr' nsmaster.nic.fr. hostmaster.nic.fr. 2225269298
> 3600 1800 3600000 5400] : 35 occurrences Average RTT 56 ms
> [NSID: b'dns.ix1.nic.fr' nsmaster.nic.fr. hostmaster.nic.fr. 2225269298
> 3600 1800 3600000 5400] : 4 occurrences Average RTT 116 ms
> [TIMEOUT] : 2 occurrences Average RTT 0 ms
> [NSID: b'dns.mrs.nic.fr' nsmaster.nic.fr. hostmaster.nic.fr. 2225269298
> 3600 1800 3600000 5400] : 10 occurrences Average RTT 156 ms
> [NSID: b'dns.ams.nic.fr' nsmaster.nic.fr. hostmaster.nic.fr. 2225269298
> 3600 1800 3600000 5400] : 8 occurrences Average RTT 101 ms
> [NSID: b'dns.lon.nic.fr' nsmaster.nic.fr. hostmaster.nic.fr. 2225269298
> 3600 1800 3600000 5400] : 2 occurrences Average RTT 154 ms
> [nsmaster.nic.fr. hostmaster.nic.fr. 2225269297 3600 1800 3600000 5400] :
> 1 occurrences Average RTT 24 ms
> Test #23843409 done at 2020-01-16T15:43:10Z
>
> Note the wonders of BGP: only a minority of probes use the instance in
> New York City (the fastest one) :-(
>
> Note also that the last result comes from a transparent proxy,
> redirecting to a cache.
>
>

-- 
*Marcel Flores, PhD* | Sr. Research Scientist
research.verizondigitalmedia.com | AS15133
<https://www.peeringdb.com/asn/15133>
e: marcel.flores at verizondigitalmedia.com
13031 W Jefferson Blvd. Building 900, Los Angeles, CA 90094
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