# Update and cut over

After an app's first revision is live, a new push does not replace it automatically. The new revision builds and launches alongside the running one, holds its own address, and surfaces on the **Updates** tab as **update ready**. The live route is untouched until you promote it.

## Cut over

On the **Updates** tab, **Cutover** promotes the ready revision to live. It runs on the queue and streams a toast, so the page never locks up. The cutover:

- starts the target revision if it isn't already running and waits for its address,
- re-points the route — CoreDNS and the edge — to the new revision in one publish,
- retires the outgoing revision: marks it, turns its autostart off, and by default stops it, while keeping it intact and revertible.

Cutover latency is bounded by how quickly the resolver refreshes, a matter of seconds.

Promotion is per app. Cutting over one app does not touch another. To promote a batch of apps together, see [Promote a pool of apps at once](./pooled-promotion.md).