The following tutorial will show you the purpose and configuration of extra destination URLs.(Please click on the images to enlarge them)
The first step is to navigate to where extra destination URLs can be found. Go to Offer>>Manage>>Select Offer. This will get you to a general information page that has an Extra Destination URLs section found at the bottom right.
Base destination URLs are the offer tracking links, but extra destination URLs are also tracking links but they go to different offer pages. This allows you to add multiple landing pages to one offer and not have to create completely separate offers.
This is the page you are linked to when you select Add under the section Extra Destination URLs.
Extra destination URLs have similar structures to base destination URLs, except they should have some identifying factor like a Sub ID to denote one of multiple placements of a single offer.
Simply fill in the name, select a status, and choose a destination URL. Click Add when finished.
This will now add this extra destination URL to the offer. You can then pull a unique link for this specific extra destination URL in the same place you go to pull the regular offer links for affiliates/partners/publishers. To learn how to pull affiliate tracking links go here: Click here
The only difference when you go to pull the links is now there will be another box that says: "URL" in which you can select your base destination URL or any of the extra URLs you have added to the offer. You can even create a smart link and rotate destination URLs and the base URL at random.