In case of problems

If you are a DNS operator and you believe your authoritative name servers may be experiencing problems due to our measurements, please consult the information below on what you can expect to see from us, how you can contact us, and as a last resort how you can block our traffic.

We thank you in advance for working with us to resolve any issues, and apologise in advance if we have inadvertently caused problems through our measurement.

What can DNS operators expect?

Forward DNS measurements

As a DNS operator, you can expect that our measurement system will send you 11 queries per day per domain you operate, and in case the domain is DNSSEC-signed, 12 queries. The system has been designed to distribute measurements over time, to reduce the impact the measurement has on busy name servers that are authoritative for large numbers of domains. We regularly inspect flow information about our measurements to monitor query rates. In general, only if you operate a very busy name server in terms of numbers of domains, should our measurement be visible in statistics.

Reverse DNS measurements

As a DNS operator, you should see a single PTR query for every IP address for which you manage the reverse DNS name space. Our measurement uses a randomisation approach to spread the load over the day. Unless you manage significant parts of the reverse name space (e.g. larger than a /16 prefix in IPv4), you should not see very high query loads from our measurement system. You may also see sporadic SOA and NS queries at delegation points in the name space.

If you are a DNS operator and you feel our measurement is impacting your infrastructure, please read on.

Note: our traffic originates from two IPv4 /24 prefixes and from two IPv6 /64 prefixes. In both cases, one prefix is used for the forward DNS measurement, and the other prefix is used for the reverse DNS measurement. All four prefixes have detailed contact information in the RIPE database. This information may prove helpful if you decide you need to block our traffic (see below).

What should I do if the measurement impacts my infrastructure?

As we believe in responsible network measurement practices, we have taken care in designing our measurement such that it should not impact DNS servers adversely. Nevertheless, it is not up to us to judge if our measurement impacts your infrastructure as a DNS operator. Therefore, if you think our measurement is impacting your infrastructure adversely, please contact us so we can try to resolve the problem. We would prefer to include the domains you operate in our measurement if possible, but of course without causing problems.

If you decide to contact us, it would help if you can provide us with the following information:

  • The name of your organisation, and a point of contact (e-mail, and if possible a phone number);
  • The DNS hostname(s) of the affected name server(s);
  • A description of the impact (e.g. number of queries per second you see, effect this has, …);
  • A date and time on which you (first) experienced problems you think may be caused by our measurement (refer to our page on current Coverage for more information on when measurements started for a particular TLD);
  • The IP address(es) or blocks from which you are receiving problematic traffic (this will help us determine if the traffic is actually coming from us, and if so, if it is only coming from a single measurement host or from multiple systems; also note that our measurement systems have both IPv4 and IPv6 connectivity).

Blocking our traffic

If you decide you need to block our traffic, we would highly appreciate it if you contact us about this. As mentioned above, our traffic always originates from fixed IPv4 /24 prefixes and fixed IPv6 /64 prefixes. If the traffic that is causing you problems does not follow this pattern it is most likely not coming from us. Upon request, we can disclose the specific prefixes from which we send traffic through private communication. We ask for your understanding for not publishing this information publicly.

Response time

We are in the Central European Timezone (UTC+1 in winter, UTC+2 in summer). We try to answer any request concerning problems within one business day. If you need our urgent attention, please include “[URGENT]” in the subject line of any e-mail you send us.

More information

You can read more about how our measurement works on our Background page.