[dns-wg] Slight Increase in DNS Resolvers Doing Priming Queries after .arpa Signing - Why?

[Apologies for duplicates]

In the latest blog on RIPE Labs, we discuss priming queries to K-root:
http://labs.ripe.net/content/slight-increase-dns-resolvers-doing-priming-queries-after-arpa-signing-why

We have seen a slight increase in the number of sources that issue
priming queries to K-root since 18 March,  the day after the signed
.arpa zone was rolled out. This increase is visible on three out of five
global nodes and seems to be caused primarily by resolvers that are not
EDNS capable.

While this is not causing any significant operational strain on K-root,
and we don't believe a significant number of clients have problems with
DNS resolution, we still want to know what is going on. We plan to
further characterise this (look at TTLs) and hopefully isolate some
sources that caused this increase. If you have any insight on this, or
have suggestions on what we should look into, please let us know.

Best regards,

Emile Aben
Research Engineer
RIPE NCC