DNS gets chosen last and matters first. In any multi-provider architecture, the DNS layer is where routing decisions actually happen, which makes this comparison more consequential than it looks.
The three candidates
IBM NS1 Connect is the traffic-steering specialist: RUM-informed routing, granular policies, the control plane serious multi-CDN setups are built on. Route 53 is AWS gravity again, capable and integrated, with steering that is workable rather than sophisticated. Cloudflare DNS is fast, free at the base tier, and inseparable from the rest of its bundle. Chosen last, DNS also gets budgeted last, which is how architectures end up with sophisticated CDN spend steered by unsophisticated routing.
What steering quality means
Basic geo-routing sends Germans to Frankfurt. Real steering weighs live performance, provider health and cost, per request population. If multi-CDN is the strategy, steering intelligence is the product, and the candidates are not equivalent. Steering quality compounds with provider count: two networks behind basic geo-routing capture a fraction of the value the same two networks deliver behind performance-aware steering.
Resilience of the DNS layer itself deserves a paragraph, because it is the component whose failure nothing else can route around. Whatever steers your traffic must itself be redundant: secondary DNS arrangements, provider-diverse nameservers, and honest answers about what happens to routing when the routing layer degrades. The historical incidents that hurt most were not CDN outages but DNS outages, precisely because every fallback plan assumed name resolution would be there to execute it. Architect the control plane to the same standard as the data plane, or the diagram is decorative.
Pricing shape
DNS pricing runs on zones, records and query volume, small numbers with large operational consequences. NS1 sits at the premium end and earns it in steering; the others price as utilities. We quote NS1 against your query profile as part of any multi-CDN design. Utility pricing is fine for utility jobs: single-CDN architectures with simple failover needs genuinely do not require the premium control plane, and pretending otherwise would be selling.
In practice
Match the DNS layer to the architecture’s ambition: single CDN, take the utility option nearest your stack and spend the savings on cache tuning. Multi-CDN with real steering ambitions, price the specialist control plane as part of the architecture rather than as an accessory, because it is the component doing the deciding. The assessment quotes it that way by default.
The DNS layer decides whether multi-CDN is an architecture or a diagram. The assessment treats it that way.