This feature is currently limited to video ads.

Within an ad response, a primary winner and a fallback ad are returned together. A fallback ad may be shown if and only if a primary winning ad fails to load or render.

For a video pod, the backup ad must not have any position targeting. In other words, the backup ad must be eligible to show in all positions of a pod, so that if the backup ad replaces the primary winners, the position targeting for the ad break remains. Additionally, the duration of a backup ad can't be longer than the longest primary ad within the pod.

Types of ads that can be served as fallback:

  • Reservation
    • Guaranteed: Standard and Sponsorship
    • Non-guaranteed: Price Priority, Remnant, and Bulk
    • House
  • Preferred Deals
  • Private Auction
  • Open Auction
  • Open Bidders

Types of ads that cannot be served as fallback:

  • Programmatic Guaranteed

Minimum bid to win (MBTW)

The MBTW value for a fallback ad is the same as the MBTW for a rejected ad. This means that for single-ad requests, for example, the MBTW for a fallback ad will be equal to the lowest winning bid. For a pod, any exclusion and/or duration constraints affect the MBTW so that the MBTW of a backup winner may be higher than the lowest winning bid


An ad response may look something like this:


Bid value

Status code


Primary winning ad




Fallback ad




Rejected ad




The difference between fallback ads and mediation chains

Mediation chains work for single-ad requests, both video and non-video formats. Publishers can set up multiple networks in a mediation chain and each network has an opportunity to fill an ad request. Ad serving attempts to fetch ads from each network in sequence.

Fallback ads apply to video ads for single-ad requests (reservation ads are supported, Ad Exchange ads are soon-to-be supported by Ad Exchange-in-waterfall) and for video pods (ad buffet). They apply to winning ads within a single auction, instead of among multiple networks. When the primary winning ad within an auction fails to serve, the fallback ad is shown as long as publisher set controls  are met. In addition, ads excluded by primary winners cannot be selected as fallback and mutually exclusive ads cannot be selected as fallbacks simultaneously.

See additional details on video fallback.


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