DNS query for a period

Has anyone every seen a DNS query for just a period?

I'm trying to figure out if the way my logs are being collected is causing this to show a DNS query as soon period or if there's hosts querying for a period.

I found one article on like SANs indicating that it may be dos activity that is related to a Porn site but nothing else.

Any help would be great.

P.s. the log only shows a period, not a fqdn then a period at the end. Which I personally think the log is possibly showing me the period at the end that's being stripped into a new log.