Azure Front Door Cache Hit Ratio Issue by Country

Question

Azure Front Door Cache Hit Ratio Issue by Country

航鈴木 20

I have enabled "Enable caching" in the route settings of Front Door Manager within Azure Front Door.

When I checked the cache hit ratio by country in Analytics > Reports > Traffic by Location, I found that some countries have significantly low cache hit ratios.

This issue has been occurring for several months, not just recently.

Could you please provide detailed investigation methods and improvement measures for the above?

G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-13T05:34:35.0933333+00:00

Hello 航鈴木

Following up to see if the above suggestion was helpful. And, if you have any further query do let us know.
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-16T07:39:31.09+00:00

Hi 航鈴木

Following up to see if the above information was helpful. And, if you have any further query do let us know.

Please don’t forget to close the thread by clicking "Accept the answer" and "Yes" wherever the information provided helps you, as this can be beneficial to other community members.
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-24T05:51:56.33+00:00

Hi

Following on this thread.

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G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-24T05:52:02.3866667+00:00

Hi

Following on this thread.

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1 answer

Your answer

G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-13T05:34:35.0933333+00:00

Hello 航鈴木

Following up to see if the above suggestion was helpful. And, if you have any further query do let us know.
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-16T07:39:31.09+00:00

Hi 航鈴木

Following up to see if the above information was helpful. And, if you have any further query do let us know.

Please don’t forget to close the thread by clicking "Accept the answer" and "Yes" wherever the information provided helps you, as this can be beneficial to other community members.
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-24T05:51:56.33+00:00

Hi

Following on this thread.

If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-24T05:52:02.3866667+00:00

Hi

Following on this thread.

If this answers your query, do click Accept Answer and Yes for was this answer helpful. And, if you have any further query do let us know.

Answer 1

G Sree Vidya 2,605 Microsoft External Staff Moderator

Hi 航鈴木

We understood that you need to check why some countries low cache hit ratios while using Azure Front Door's caching feature.

Here are a few investigation methods and improvement measure you can try:

Ensure that the caching rules are correctly configured for each routing rule. Make sure that caching is enabled and that the rules aren’t inadvertently set to disable caching for specific content types or origin responses.
Review Analytics Reports: Use the Analytics > Reports > Traffic by Location section to analyze the cache hit and miss counts. This can help identify specific countries with low ratios and potentially correlate issues with specific content or request types.
Refer:https://learn.microsoft.com/en-us/azure/frontdoor/standard-premium/how-to-reports?tabs=traffic-by-domain
Try to analyse the edge site behaviour where Each Azure Front Door edge site manages its own cache. A request from one country may hit a different edge site than another, leading to:
- Cold cache in some regions
- Inconsistent cache population
Investigate Cache Control Headers: Review the origin response headers for requests from countries with low cache hit ratios. Look for headers like Cache-Control, Pragma, or any other cache-related settings that might indicate content should not be cached. Ensure that you're not sending headers that prevent caching.
If you're using geo-filtering, check if there are restrictions that could be affecting which content is being cached based on location.
Keep monitoring the caching report over time to look for trends. It can help in identifying patterns, such as times when cache hits improve or decline.

Could you please provide detailed investigation methods and improvement measures for the above?

1.Separate Static and Dynamic Routes:

Use different paths or subdomains for static assets (e.g., /images/, /static/)
Enable aggressive caching for static routes

2 Monitor and Tune Regularly:

Use Azure Monitor and Log Analytics to track cache hit/miss trends
Set up alerts for cache hit ratio drops in key regions
Refer: https://learn.microsoft.com/en-us/azure/frontdoor/monitor-front-door?pivots=front-door-standard-premium

I hope this information is helpful! If my answer helped you resolve your issue, please consider marking it as the correct answer or Upvote. This helps others in the community find solutions more easily. Thanks!

航鈴木 20 Reputation points

2025-06-20T01:02:50.11+00:00

Hi @G Sree Vidya

Thank you for your answer.

I have one additional question.

You mentioned, "and that the rules aren’t inadvertently set to disable caching for specific content types or origin responses."

However, I understand that Azure Front Door's caching feature only allows for enabling caching through the Front Door Manager, and that detailed settings such as caching for specific content types, as you mentioned, are not available.

Where can I configure these detailed settings? Could you please explain how to configure them?
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-20T05:57:41.4066667+00:00
Hello 航鈴木

Thank you for your follow-up question regarding configuring detailed caching settings for specific content types in Azure Front Door.

Your understanding is correct that the Front Door Manager primarily allows enabling or disabling caching at the route level.

However, to configure detailed caching settings, such as for specific content types or origin responses, you can use the Rules Engine in Azure Front Door (Standard or Premium tiers).

You can configure these settings in the Rules Engine of Azure Front Door (Standard or Premium tiers).

Here’s a step-by-step guide to configure:

Go to your Front Door profile in the Azure portal.

Navigate to Rules Engine.

Click + Add Rule Set or edit an existing one.

Define Match Conditions, such as:

Request Path ends with .jpg

Request Header contains application/json

Add Actions, such as:

Cache expiration → Override TTL (e.g., 7 days)

Modify response header → Add or change Cache-Control

Associate the rule set with your route in the Front Door Manager.

Please refer this document for more information: https://learn.microsoft.com/en-us/azure/frontdoor/front-door-caching?pivots=front-door-standard-premium

https://learn.microsoft.com/en-us/azure/frontdoor/rules-engine-scenarios?tabs=portal
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-23T01:26:51.3933333+00:00

Hi

We haven't heard back from you regarding our last response and wanted to check if you had the opportunity to review our previous post.

Please let us know if you have any questions or concerns. We are happy to assist you.
航鈴木 20 Reputation points

2025-06-26T00:43:07.5933333+00:00

Thank you for the additional response.

Based on the information you provided, I have checked the settings, but I couldn't find any configurations that would disable caching for specific content types. Also, upon examining the response headers, I found no issues with cache-related settings such as Cache-Control. However, after rechecking the cache hit ratio under "Analytics" > "Reports" > "Traffic by Location," the cache hit ratio remains low only in specific countries.

Country Cache Hit Ratio

US 2.87%

Japan 57.14%

India 86.42%

Are there any other possible causes besides the information you have already provided?
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-27T07:39:20.02+00:00

Hi 航鈴木

Apologies for the delay,

Azure Front Door primarily supports caching for static assets such as images, CSS, JavaScript, and HTML files. Please review the types of content currently enabled for caching in your Front Door configuration (ADF) to ensure they are suitable for caching.

It's important to note that dynamic content (such as personalized or frequently changing data) is not cached by default. Caching such content requires explicit configuration using the Rules Engine.

https://learn.microsoft.com/en-us/azure//frontdoor/front-door-caching?pivots=front-door-standard-premium

Additionally, Front Door does not guarantee that content will be cached in every Point of Presence (POP). Caching behavior depends on how frequently the content is requested from a specific region. If a user in a particular country (e.g., the US) requests content for the first time, that request will go to the origin and populate the cache. Subsequent requests from that region may then be served from the cache, depending on TTL and cache eviction policies.

This behavior could explain the low cache hit ratio in specific countries, especially if traffic volume is lower or more diverse in those regions.
G Sree Vidya 2,605 Reputation points Microsoft External Staff Moderator

2025-06-30T17:53:51.46+00:00

Hi 航鈴木

Just checking in to see if below information was helpful. If you have any further updates on this issue, please feel free to post back.

.

Country	Cache Hit Ratio
US	2.87%
Japan	57.14%
India	86.42%

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Azure Front Door Cache Hit Ratio Issue by Country

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