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# Domain Architecture

> How tieback serves Digital Product Passports from platform subdomains and verified custom hostnames, and how resolver requests are routed at the edge.

tieback supports flexible domain configuration for Digital Product Passports. Brands can serve passports from platform subdomains or their own custom hostnames.

## Domain Models

### Platform Subdomains

Every brand on tieback receives a platform subdomain:

```
https://<brand>.tieback.io
```

This subdomain is immediately available after onboarding and supports all resolver paths and public passport pages.

**Example:**

```
https://mybrand.tieback.io/01/5060999100032
```

### Custom Hostnames

Brands can configure a custom hostname to serve passports from their own domain:

```
https://passport.mybrand.com/01/5060999100032
```

Custom hostnames are provisioned via Cloudflare for SaaS and require a DNS CNAME configuration. See the [DNS Setup Guide](/domains-custom-hostnames/dns-setup-guide) for details.

## What a Consumer Experiences

### From Scan to Passport

When a consumer scans a QR code or follows a Digital Product Passport link, the request to your domain resolves to that product's passport. The scan URL is matched to the product identity it encodes, and the consumer lands on the published passport page for that product.

Resolution is fast, cached at the edge, and requires no app or account.

### Hostname Preservation

The original hostname is preserved throughout. Whether the request arrives via a platform subdomain or a custom hostname, the passport is served on the same hostname, so the consumer stays on the brand's domain throughout the journey.

### Supported Path Prefixes

| Prefix                   | Type             | Description                              |
| ------------------------ | ---------------- | ---------------------------------------- |
| `/01/<GTIN>`             | GS1 Digital Link | Standard GTIN-based product identifier   |
| `/01/<GTIN>/10/<lot>`    | GS1 Digital Link | Product identifier with lot/batch number |
| `/01/<GTIN>/21/<serial>` | GS1 Digital Link | Product identifier with serial number    |
| `/mu/<id>`               | Mint Unit        | Direct mint unit identifier              |
| `/mb/<id>`               | Mint Batch       | Batch-level identifier                   |
| `/ml/<id>`               | Mint Lot         | Lot-level identifier                     |
| `/p/<id>`                | Passport Page    | Public passport rendering destination    |

## Custom Hostname Path Policy

Custom hostnames support **public consumer paths** only:

| Path                               | Supported | Purpose                                    |
| ---------------------------------- | --------- | ------------------------------------------ |
| `/01/*`, `/mu/*`, `/mb/*`, `/ml/*` | ✅ Yes     | Resolver paths: scan entry points          |
| `/p/*`                             | ✅ Yes     | Public passport page rendering             |
| `/dashboard`, `/settings`, etc.    | ❌ No      | Application routes: use platform subdomain |

Dashboard and application access should continue to use the platform subdomain (`<brand>.tieback.io`) or the main application URL (`app.tieback.io`).

## Platform Support

tieback supports both domain models simultaneously:

* **Start with a platform subdomain**: available immediately after onboarding
* **Add a custom hostname later**: configure when ready, with no disruption to existing QR codes
* **Both active at the same time**: platform subdomain always remains available as a fallback

## Getting Started

1. Your platform subdomain is available immediately after brand onboarding
2. To set up a custom hostname, follow the [DNS Setup Guide](/domains-custom-hostnames/dns-setup-guide)
3. Custom hostnames must be verified before they become active

## Related Docs

* [Custom Hostname Setup](/domains-custom-hostnames/custom-hostname-setup)
* [DNS Setup Guide](/domains-custom-hostnames/dns-setup-guide)
* [Resolver Domain Flow](/domains-custom-hostnames/resolver-domain-flow)
* [Custom Hostname Troubleshooting](/domains-custom-hostnames/troubleshooting)