Random nx name queries, anyone see this before?

[ponga2112 at gmail.com]

I'm seeing name queries from a couple clients on the network that
occur around every two minutes - the queries are evidently random and
are looking for A IN records of this form, as an example:

ungzbvyf.lzghmccim

They always look like this, 8 lowercase chars, dot, then 9 lowercase
chars - never an FQDN.
I can't find what this might be - has anyone seen this before or have
any ideas?

TIA,
ponga