I get mail from logcheck daily and the l ... / 2008-05-26

I get mail from logcheck daily and the last week or so on one nameserver I keep seeing variations of

May 26 09:37:15 gosper named[895]: denied query from [66.238.93.161].26906 for "." NS/IN
May 26 09:56:16 gosper named[895]: denied query from [211.72.249.201].13819 for "." NS/IN

All the time those 2 IPv4 addresses. With one or two tries it might be a simple attempt to fingerprint my nameservers but at this rate it seems like an attempt at a denial of service attack. Interesting is that the amount of requests is exactly the same for both IPs. 66.238.93.161 and 211.72.249.201 are registered to parts of Asus computers.. where I recently downloaded a bios update in order to fix some acpi problems. Related?