VAST versions in CTV: what is the difference between VAST 2, 3, and 4?

VAST (Video Ad Serving Template) is the IAB standard that defines how a video ad is delivered and tracked. Key differences: VAST 2.0 is the baseline — supports pre/mid/post-roll video, basic tracking events (impression, start, quartile, complete), and simple companion banners. VAST 3.0 adds ad pods (multiple ads in a single break), skip offset parameters for skippable ads, and error reporting improvements. VAST 4.0 adds universal ad ID (for deduplication), interactive creative support (SIMID), separate media file verification (VAST 4.1+), and improved macro support for dynamic creative. Most India CTV publishers support VAST 3.0 minimum; JioHotstar and Google-served inventory support VAST 4.x.

Use VAST 3.0 as your baseline creative spec for India CTV — it is universally supported across JioHotstar, Sony LIV, Zee5, and smaller publishers. Use VAST 4.0 when: you need universal ad ID for cross-publisher deduplication, you are running interactive CTV ads (SIMID-dependent), or the publisher specifically requires it. Avoid VAST 2.0-only creatives as they will not support ad pod positioning signals or skip offset controls — relevant for campaigns buying non-skippable 15s or skippable 30s. If a publisher’s player returns a VAST 101 error code (VAST version not supported), the mismatch is usually between a VAST 4.0 tag served to a VAST 3.0 player — check the publisher’s accepted VAST version in the deal specs.

A VAST wrapper is a VAST response that points to another VAST tag (the “wrapped” tag) rather than directly to a video file. Wrappers are used to chain multiple ad servers: the SSP returns a wrapper pointing to the DSP, which returns a wrapper pointing to the verification vendor, which returns the final inline VAST with the actual video URL. Each wrapper requires an additional HTTP request, which adds latency. In India, network latency means each wrapper adds 100–300 ms. CTV players typically enforce a wrapper chain limit of 3–5 levels — if the chain is too deep, the player abandons the request and fires a VAST 302 (wrapper timeout) or 303 (no fill) error. Keep wrapper chains to 3 levels maximum for India CTV to avoid fill failures in lower-bandwidth conditions.