Why is my single front door service causing double charges?

Hello Sandro Rudin

It seems like you're experiencing an issue with your Azure Front Door service showing double charges, which is definitely puzzling. Since you're connected to two domains and expecting a single charge, here are a few things to consider:

1. Request Processing Fees: Each request that Front Door processes incurs fees. If both domains are generating requests, it could lead to charges that might feel like double billing. Each request is measured against the Host header. So, depending on traffic, you'll be billed for each domain's requests separately.
2. Data Transfer Charges: If both domains are also transferring data, you might see additional billing. Front Door charges for data that moves from its edge location to your origin server, which could also contribute to increased costs.

Refer this article: Understand Azure Front Door billing

To get to the bottom of the double charges, here are some recommended steps:

• Analyze Your Costs: Use Azure Cost Management to break down the charges and identify where they originate. Check the Explore and analyze costs with cost analysis for guidance.
• Review Your Bill: Look into the invoices to determine how the charges for Front Door are being calculated. The Review invoiced charges in cost analysis article can help you understand your bill better.
• Check for Duplicate Resources: Ensure there are no duplicate Front Door resources or services set up under your account which might inadvertently account for the double charges.

If this doesn’t resolve the issue, could you please clarify the following?

1. Are there any specific metrics or records from the billing that you find confusing?
2. Have you checked whether the load between the two domains leads to different traffic patterns?
3. What SKU of Azure Front Door are you currently using, and has there been any recent change to the configuration?

Hope this helps clarify the situation! Let me know if you need further assistance!

Relevant Documentation Links:

• Understanding Azure Front Door billing
• Explore and analyze costs with cost analysis
• Review invoiced charges in cost analysis

I hope this was helpful!

If the above is unclear or you are unsure about something, please add a comment below.