Measuring the impact of locally served root zone

In this episode of PING, we talk with Willem Toorop from NLNet Labs and Ilyas Rahimi who recently completed a masters in Security and Network Engineering at the University of Amsterdam (UvA). They’ve been looking at the effects of local root serving.

Ilyas was on a masters programme called “OS3” at UvA (from the triplet of Open Standards, Open Software and Open Security). NLNet labs is on the campus of UvA and Willem has been working with the masters programme for some time, pursuing research in DNS and DNSSEC with the students doing their masters thesis component. They conduct 2 1-month original research activities in the masters course, and write the second one up as their masters thesis.

Locally served root is a model of operating a DNS resolver where it “pre-fetches” the state of the root zone, the apex of the entire DNS naming model. By fetching this data the idea is that both early termination of unresolvable domain names (names where the final terminal label can be seen not to exist under the root of the DNS) and a degree of privacy in fetching resolvable names can be gained, by looking in the local copy. There is a current proposal in the IETF to make this a “best current practice” or BCP.

Ilyas looked at 3 different public code-bases (bind, unbound and the knot DNS resolver) and a total of 4 configurations, exploring both in-band and HTTPS bound fetch of the root zone.

As well as identifying a bug in the model unbound used, which accounted for a spike in traffic, Ilyas has been able to show that under the update cycle typically seen for the root there is a surprising increase in apparent network traffic fetching the zone, compared to the many but far smaller events asking for uncached data from the roots.

There is more work to do in this space, and with the OS3 masters thesis component now given more time in the degree program, there is hope that Willem can continue to work with UvA students, and carry forward the measurements. WIllem has been exploring how the system behaves if converted to incremental updates (IXFR) rather than an entire zone-fetch.