Comment by justinsaccount

In my experience that sort of thing is from the local hostname not being present in /etc/hosts and (of course) a caching resolver not in use.

Some process on the system wants to connect to itself, which then causes a dns lookup. Add a high transaction rate on top of that, and 1,200/second is easy.

The funniest one I remember seeing was thousands and thousands of lookups for HTACCESS. Turned out apache was running on top of a web root stored in AFS and not configured to stop looking for .htaccess files at the project root, so it would try to open

  /afs/domain.com/app/.htaccess
  /afs/domain.com/.htaccess
  /afs/.htaccess

When it hit /afs/.htaccess then it would try to contact the AFS sell called .htaccess, which would do a bunch of dns lookups.

This would be done something like twice for every incoming web request.