Azure Front Door

• A service that uses Microsoft’s global network to improve the availability and performance of your applications to your local and global users.
• It works at the HTTP/HTTPS layer and uses a split TCP-based anycast protocol to ensure your users connect to the nearest Front Door point of presence.
• Supports a range of traffic-routing methods and backend health monitoring options for various application needs and automatic failover models.
• With URL-based routing, it routes the traffic to backend pools based on URL paths of the request.
• You can configure more than one website on the same Front Door with multiple-site hosting.
• Use cookie-based session affinity to redirect the user session to the same application backend.
• Redirect traffic based on protocol, hostname, path, and query string with URL redirect.

• URL rewrite allows you to configure a Custom Forwarding Path that will copy any part of the incoming path that matches a wildcard path to the forwarded path.
• Front Door supports end-to-end IPv6 connectivity and HTTP/2 protocol.

Security

• If you need your domain name to be visible in your Front Door URL, you must have a custom domain. Front Door also supports managed certificates or custom TLS/SSL certificates.
• You can create custom rules to protect your HTTP/HTTPS workload from exploitation using Azure Web Application Firewall.

Pricing

• You are charged based on the following:
  • Inbound and outbound data transfers
  • The number of routing rules
• Front Door has a limit of 100 custom domains. You will be charged for additional domains.

Sources:
https://azure.microsoft.com/en-us/services/frontdoor/
https://docs.microsoft.com/en-us/azure/frontdoor/front-door-overview