Host behind Front Door that serves the content, such as an App Service app, storage, a load balancer or any custom host given by FQDN. An App Service app counts as one origin regardless of its worker count.
Also called Backend (Front Door classic).
Read more: Microsoft Learn
In the Ultra Transcenders books
Each book explains Origin in context, with comparison tables and the common traps.
Terms in this definition
- App Service
Managed PaaS hosting for web apps and Web App for Containers, run in a sandbox without OS access. Deployment slots and autoscale start at the Standard tier.
- App protection policy
A set of Intune rules on managed apps that safeguards organisational data, for example by demanding a PIN or preventing copy-paste and save-as into personal apps. It works whether or not the device is enrolled.
- General-purpose v1
The older storage account kind (
Storage), which lacks access tiers, Archive and premium file shares and retires on 13 October 2026. Converting to ZRS requires first upgrading to GPv2, a one-way change. - ELT
Extract, load, transform: raw data lands in the target system first and is transformed there. See ETL for the opposite order.
- FQDN
The full DNS name of a host, zone included, for example www.contoso.com.
- Worker
A classic compute node hosting a Spark executor that carries out distributed work; with one executor on each worker the two words are used as synonyms. Worker node type sets its instance family, and Spark commands fail if there are no workers.
- COUNT
A DAX function returning how many non-blank numbers, dates or text values a column contains. Boolean columns need COUNTA instead, and for counting the rows of a table COUNTROWS is the better choice.
Related terms
- AzureFrontDoor.FirstParty
Service tag that Microsoft reserves for its own Front Door-hosted services; locking down your origin is not what it is for.
- Latency sensitivity
Setting on a Front Door origin group, in milliseconds and 0 by default, that extends the range around the quickest origin; every origin within that range receives traffic according to its weight.
- Origin group
Collection of Front Door origins that share health probe and load-balancing settings (latency, priority and weight). Choosing an origin by path is never done at this level.
- Private Link origin
In Azure Front Door Premium, an origin (App Service, Storage or an internal load balancer) reached through a managed private endpoint that Front Door creates and the origin's owner approves.
- Source group
Composite models divide items by origin: everything from one DirectQuery source forms one group, while import plus Direct Lake items together form another. Relationships spanning two groups are always limited.
- X-Azure-FDID
Lets an origin accept requests from just one particular Front Door instance, since this HTTP header carries the ID of the Front Door profile.