# Life of a Vercel request: Application-aware routing

By Steven Van · 2025-04-15

Vercel explains how its gateway uses framework code to route requests, roll back instantly and keep frontends and backends on the same deployment.

Routing on [Vercel](<https://creatorstoolbox.com/tools/vercel>) is built into the platform as an application-aware gateway, not configured separately in a caching layer, according to [the second part of the "Life of a Vercel request" series](<https://vercel.com/blog/life-of-a-request-application-aware-routing>). The gateway reads routes, layouts, rewrites, middleware, functions and static assets from your framework code. That lets it make decisions such as skipping unnecessary compute.

The post walks through how a request is handled and what that design allows:

- **Aliases:** every domain, whether custom, third-party or \*.vercel.app, is an alias that maps to one deployment. Vercel provisions and manages SSL/TLS certificates when a domain is aliased.

- **Request path:** a request goes through Anycast routing to the nearest Point of Presence, then DDoS mitigation and a first Web Application Firewall check in a Vercel Region. It is then de-aliased to its deployment. Because the WAF has the deployment's routing metadata, firewall rules can target parts of the application rather than only raw paths or regex patterns.

- **Instant rollbacks:** switching an alias to a previous deployment propagates globally within milliseconds, with no DNS propagation, warmup or rebuild. The CDN cache stays intact.

- **Incremental rollouts:** traffic can be split between two deployments for phased, blue/green style releases. A rollback returns the traffic to the earlier deployment.

- **Skew Protection:** requests in a session are routed to the same deployment, which keeps frontend and backend code from different deployments from mismatching.

![Vercel](<https://www.google.com/s2/favicons?domain=vercel.com&sz=128>)

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[Original source](<https://vercel.com/blog/life-of-a-request-application-aware-routing>)

[Read Life of a Vercel request: Application-aware routing on Creators Toolbox](<https://creatorstoolbox.com/blog/vercel-life-of-a-vercel-request-application-aware-routing>)

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Canonical source: https://creatorstoolbox.com/blog/vercel-life-of-a-vercel-request-application-aware-routing