1 research outputs found
Measuring DNS over TCP in the Era of Increasing DNS Response Sizes: A View from the Edge
The Domain Name System (DNS) is one of the most crucial parts of the
Internet. Although the original standard defined the usage of DNS over UDP
(DoUDP) as well as DNS over TCP (DoTCP), UDP has become the predominant
protocol used in the DNS. With the introduction of new Resource Records (RRs),
the sizes of DNS responses have increased considerably. Since this can lead to
truncation or IP fragmentation, the fallback to DoTCP as required by the
standard ensures successful DNS responses by overcoming the size limitations of
DoUDP. However, the effects of the usage of DoTCP by stub resolvers are not
extensively studied to this date. We close this gap by presenting a view at
DoTCP from the Edge, issuing 12.1M DNS requests from 2,500 probes toward Public
as well as Probe DNS recursive resolvers. In our measurement study, we observe
that DoTCP is generally slower than DoUDP, where the relative increase in
Response Time is less than 37% for most resolvers. While optimizations to DoTCP
can be leveraged to further reduce the response times, we show that support on
Public resolvers is still missing, hence leaving room for optimizations in the
future. Moreover, we also find that Public resolvers generally have comparable
reliability for DoTCP and DoUDP. However, Probe resolvers show a significantly
different behavior: DoTCP queries targeting Probe resolvers fail in 3 out of 4
cases, and, therefore, do not comply with the standard. This problem will only
aggravate in the future: As DNS response sizes will continue to grow, the need
for DoTCP will solidify.Comment: Published in ACM SIGCOMM Computer Communication Review Volume 52
Issue 2, April 202