Problem:This is a common scenario. You are using tinyMCE in admin of a site to insert a link to image. While displaying that image on frontend tinyMCE makes it relative path instead of absolute.
When setting up tinyMCE set these 2 configuration options:
relative_urls : false
remove_script_host : false
Both these options are true by default. As the name implies, “remove_script_host” removes the protocol and host part of URLs. “relative_urls” must be set to false is you want to set “remove_script_host” to false.
Hope it helps.