Thank you very much, makes perfect sense. Can we increase the timeout somehow or specify it as a tunable query parameter? I find the OARC tester highly useful in conjunction with RIPE ATLAS. <div class="gmail_quote">On Dec 26, 2015 12:24 PM, "Anand Buddhdev" <<a href="mailto:anandb@ripe.net">anandb@ripe.net</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On 24/12/15 10:59, Gil Bahat wrote: Dear Gil, > Unfortunately, this doesn't seem to work so well either: > <a href="https://atlas.ripe.net/measurements/3115499/" rel="noreferrer" target="_blank">https://atlas.ripe.net/measurements/3115499/</a> > 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 </blockquote></div>