Cutover
The point in a migration at which production traffic is switched from the old environment to the new AWS environment, typically the highest-risk moment in the whole project.
Definition
Cutover is the moment a migration moves from preparation to production: DNS is repointed, traffic is redirected, and the AWS environment becomes the live system rather than a parallel one. Everything before cutover (data replication, testing, dry runs) exists to make this moment as uneventful as possible; everything after it depends on how well the rollback path was planned in case something breaks.
In Practice
A well-planned cutover for a customer-facing application often happens in a low-traffic maintenance window, with a rehearsed step-by-step runbook and a clear rollback trigger agreed in advance, not decided under pressure.