John L. Crain writes in the ICANN blog on what you can learn from running a DNS server that serves the root. John writes this gives an interesting view into the world of the DNS. With the ongoing improvements to the ICANN operated L-ROOT ICANN has been fortunate enough to be able to make use of the â€œDNS Statistics Collectorâ€ tool.
John goes on to say â€œDSCâ€ allows us to generate different views of the DNS queries we have been seeing at the L-ROOT systems. Both to the current IP address (220.127.116.11) and to the old address (18.104.22.168).
A graph is included in the posting that shows commonly queried Top Level Domains for a single day and the type of queries being asked. These are queries seen across l.root-servers.net. The TLDs change from day to day but some are persistent.No surprises in there really although some of the TLDs being queried should raise a few eyebrows.Seeing mainly addresses record queries (A and AAAA) for .com or .net, or a lot of requests for reverse delegation informations (PTR) in .arpa are logical things to see.However, â€œ.localâ€ is constantly in the top five of queries which is likely an indication of misconfiguration somewhere. Regular appearances are also made by â€œ.localhostâ€, â€œ.belkinâ€, â€œ.homeâ€, â€œ.invalidâ€, â€œ.localdomainâ€ and â€œ.domainâ€.I leave it to the reader to decide why this is and at whom to point fingers.
John concludes that clearly one thing is certain, a large portion of the queries we are seeing are for non existing domains and hence get answered with â€œNXDOMAINâ€. Oh and one last snippet of information from John. He knows that sometimes people do not allow DNS queries over TCP. This is actually not a good idea. According to the RFCs it is OK to query over TCP and in the case of a large enough answer (over 512 bytes) then TCP is typically the way to get that. So although the number of TCP queries is small compared to those using UDP, they can be valid queries.
To see this posting on the ICANN blog with graphs, see blog.icann.org/?p=240