鯖のsyslogが太ってる

急激にログが記録されているsyslogに何が書かれているのかと覗いてみると
May 15 10:02:19 atcom named[6426]: client 72.20.26.1#57659: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:19 atcom named[6426]: client 72.20.26.1#10565: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:19 atcom named[6426]: client 72.20.26.1#54619: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:21 atcom named[6426]: client 72.20.26.1#27267: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:21 atcom named[6426]: client 72.20.26.1#18769: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:22 atcom named[6426]: client 72.20.26.1#12919: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:22 atcom named[6426]: client 72.20.26.1#28033: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:23 atcom named[6426]: client 72.20.26.1#3508: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:24 atcom named[6426]: client 72.20.26.1#19765: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:24 atcom named[6426]: client 72.20.26.1#35671: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:24 atcom named[6426]: client 72.20.26.1#44265: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:26 atcom named[6426]: client 72.20.26.1#43211: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:29 atcom named[6426]: client 72.20.26.1#17948: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:29 atcom named[6426]: client 72.20.26.1#13457: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:30 atcom named[6426]: client 72.20.26.1#24974: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:30 atcom named[6426]: client 72.20.26.1#57159: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:31 atcom named[6426]: client 72.20.26.1#9736: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:32 atcom named[6426]: client 72.20.26.1#36674: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:32 atcom named[6426]: client 72.20.26.1#26052: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:33 atcom named[6426]: client 72.20.26.1#33323: query (cache) 'impactpoint.ru/TXT/IN' denied
May 15 10:02:34 atcom named[6426]: client 72.20.26.1#39296: query (cache) 'impactpoint.ru/TXT/IN' denied

なんてのが山のように出てくる

DNSを利用したDOS攻撃でしょうか、取りあえずIPを蹴る