Trusted Host settings
Protecting against HTTP HOST Header attacks (prevent your site from thinking it is someone else)
Drupal 7 added a new feature into core that is not user facing directly, but is sometimes called poor man's cron. The feature triggers the periodic tasks of a Drupal site like emptying log files, sending e-mails, and clearing out caches. This feature, when combined with dynamic detection of the "base url" (added in Drupal 4.7), can lead to some screwy situations. This article is a description of some of those screwy situations that occur with either module or both of them and what you can do to prevent them. The comments below assume some default configurations - I'll discuss at the end how to break away from those defaults to prevent these problems.