Help with TLD



I needed to contact the technical support for my AV vendor, Nod32. I
sent an email to ...@xxxxxxxx and the reply I received was from
...@xxxxxxxxxxxx

I would expect eset to have domains such as eset.com, eset.com.uk,
eset.co.uk or even uk.eset.com but not eset.uk.com. I would expect
eset.uk.com to be a sub domain of uk.com domain which seems to be a
referrer/affiliate site.

Any insight? Thanks