Your entire site is served through one CDN. What happens if that provider has a global outage, and what would you do about it?

What the interviewer is testing

Whether you have thought about a dependency that is usually treated as infrastructure rather than as a single point of failure.

What happens

Your site is down, regardless of your origin's health. If the CDN also provides DNS, the domain does not resolve either, which removes the ability to redirect traffic elsewhere — a compounding failure worth calling out specifically.

This is not hypothetical. Major CDN and edge providers have had global outages, and each one takes a substantial fraction of the web with it.

The options, honestly priced

Accept it. For many businesses this is defensible: the provider's availability is likely better than what you would achieve alone, the outages are rare and short, and everyone else is down too. State it explicitly as an accepted risk with the reasoning recorded, rather than leaving it unexamined.

DNS independence. Use a different provider for DNS than for CDN, so at minimum you retain the ability to redirect. Cheap, and it is the single highest-value step — though DNS failover is eventual and partial because resolvers and application runtimes cache aggressively and frequently ignore TTLs.

Multi-CDN with health-based routing. Genuine resilience, and it costs: two contracts, two configurations to keep synchronised, cache hit rates split across providers, and features reduced to the intersection of both. Configuration drift between them is the practical failure mode.

Origin capable of serving directly, at reduced performance, as a degraded mode. Requires capacity you do not otherwise need.

The decision

Match the investment to the business consequence. For a content site, accepting the risk is reasonable. For a payment flow, a trading platform or anything where minutes of unavailability are material, multi-CDN or at least a rehearsed origin-direct path is warranted.

What a strong answer adds

Test the failover before you need it. A multi-CDN configuration that has never carried production traffic on the secondary is a configuration, not a capability — and the way it usually fails is configuration drift, where the secondary has an old ruleset.

And the regulatory dimension for financial services: this is precisely the concentration risk regulators ask about, and the expected answer is a documented and tested plan rather than an assertion.

Common weak answers

Multi-CDN proposed without pricing the operational cost. Assuming the origin can serve full traffic without checking.