A multi-CDN setup splits traffic between two or more vendors instead of trusting one with all of it. The reasons are commercial (vendors compete on price; you can demand better rates), performance (no single CDN is best in every region — Cloudflare may win in Europe, Akamai in Asia, AWS in North America), and resiliency (when one CDN has a major outage — which happens every year — you fail over to the others without viewers noticing).
The mechanics are typically: a content-steering layer at the player or at DNS picks which CDN to use for a given session. Decisions can be driven by client geo, ISP, real-user throughput measurements, real-time CDN health scores from independent probes (Cedexis/Citrix ITM, NS1, IBM Cloud Internet Services), or contract-driven traffic ratios. Players such as Shaka Player and dash.js support content steering (HLS Content Steering, DASH Content Steering, both standardised by 2023) so the player can switch CDNs mid-session without rebuffering.
Multi-CDN is expensive operationally. Each CDN needs its own configuration, monitoring, and contract management. The benefit kicks in around millions of monthly viewers — below that, the savings don't justify the complexity. Above that, every tier-1 OTT in 2026 runs multi-CDN; Netflix runs three, Disney+ runs four, sports services often run five or six for major events.
