By default, attachments do not have a version query parameter, like, for example JavaScript files have. This plugins adds version numbers to the query strings of attachments.
Version numbers in query strings are useful for caching. If an attachment changes, its version number and, therefore, its URL changes. This allows for the attachment to be cached for an extended period of time or indefintely, for example, with the directive “immutable” of the Cache-Control header.

Attachment URL Version

Adds the version number of attachments to their URL.

Sergey Biryukov

Allows to find all posts where a particular attachment (image, video, etc.) is used.
Adds a “Used In” column to the list view in Media Library, as well as to the attachment details modal.
Finds posts that use the image (including any of its intermediate sizes) in post content, or as a featured image. Works with custom post types too.
Inspired by a <a href="http://wptavern.com/the-problem-with-image-attachments-in-wordpress" rel="nofollow ugc">WP Tavern post</a> on image attachments.

Find Posts Using Attachment

Allows to find all posts where a particular attachment is used.

Attachment URL Version vs Find Posts Using Attachment