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DNS
Names to addresses, cached longer than you think. A failover that depends on DNS is a failover with a TTL.
What is DNS?
DNS maps names to records. Resolvers cache them for the TTL. Lowering TTL during an incident does not evict caches that already stored the old value. DNS is not instant service discovery, and it is a common single point if one hosted zone is wrong.
Why does DNS matter when vibe coding?
Models set TTL to 1 second “so deploys are instant,” or to a day and then expect a failover to be immediate. Name the TTL you can live with.
How do you do DNS?
Use a load balancer or virtual IP for fast failover. Use DNS for stable names. Set TTL deliberately. Do not put unique per-request data in DNS.
How do you ask a model for DNS?
Keep (name) on DNS with TTL (duration). Do not expect DNS changes to failover instantly. Fast failover belongs on the load balancer. Do not set TTL to 1 second as a habit.
What goes wrong with DNS?
Health-checking by resolving DNS from inside the same broken resolver. Check the address you serve, not only the name.