Cache busting in DFP

Cache busting in DFP (DoubleClick for Publisher)

Cache busting is a must if you are trafficking a third party ad code and want the third party ad server be able to track impressions accurately. You need not worry about this for a DFP hosted creative as DFP takes care of it by its inbuilt mechanism.

How’s cache busting done for DFP hosted creatives?

DFP automatically inserts a cor-relator value in the tag through the JavaScript libraries which are loaded to the page. The cor-relator value changes in every page load causing new request to be made to DFP in each call and thus avoiding cached browser ads.  Same cor-relator values also help DFP in identifying if all ads are coming from same page aiding in roadblocks and other stuffs.

Cache busting in third party ads?

DFP gives a provision of Cache-buster Macro(%%CACHEBUSTER%%) which can be used in your third party ad code. The macro expands to a random number, thus achieving cache busting. Every 3rd party ad code have its own placeholder for inserting Cache-buster macro and some syntax mention it as random number placeholder. You can refer the  article Third Party Macro Placement.