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Time to live

8 Aug 2026 #025 2 images

To cut DNS costs Russ raised the record TTL to a full day. When the web box died, the failover — and the fix for the TTL — sat behind twenty-four hours of cached answers.

The mistake

Raising the TTL to 86400 cuts DNS lookups exactly as asked. It also means every resolver holds the old address for a day — including during the failover, and including while trying to shorten the TTL again.

dns
caching
on-call
cloud-cost
ai-tooling