Which IPs/hosts does Drupal query for updates?
From update.module:

/**
 * URL to check for updates, if a given project doesn't define its own.
 */
define('UPDATE_DEFAULT_URL', 'http://updates.drupal.org/release-history');


Each module and theme is allowed to define it's own URL, it'll be in it's info file, but this one will cover most cases.

Note you need an access to all paths under this one, ie for Views updates Drupal will query http://updates.drupal.org/release-history/views/7.x