Azure CDN with Microsoft is not providing any expired headers or ways to check if the caching is done properly

Anonymous

Hi there,

We are using Azure CDN with Microsoft (we switched from Verizon).

With Azure CDN and Verizon it was really simple to check if something was cached and when it was expiring because of the expiry header and the age of the asset in the cache. I am no longer seen those fields.

Right now, with our Azure CDN for Microsoft, we are seeing a lot of TCP_MISS which I am currently investigating. I can see that max-age is correctly set according to our global caching rule which overrides and always sets 60 days (= 5184000 in seconds) and as seen below:

User's image

The response that I am seeing is the below. We do see a lot of TCP_HIT and TCP_REMOTE_HIT but sometimes it seems inconsistent.

Do you know if I can somehow see the age of the assets and when they expire?

User's image

Brian

KapilAnanth-MSFT 35,001 Reputation points Microsoft Employee

2023-02-02T16:38:34.4266667+00:00
@Anonymous

Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

I understand that you would like to view the expiration time of your cached content from Azure CDN from Microsoft.

You have mentioned you used to see the expires time with your previous third party CDN. Can you please elaborate how you would do so?

Using "about:cache" or using the Application section of Dev Tools, under Cache Storage?

If possible, can you please share a screenshot of one such cached content?

Coming to your scenario,

I believe this is happening because Azure CDN uses "Cache-Control" and not "Expires".

Cache-Control overrides the Expires header, if both it and Cache-Control are defined.

Can you please check if the backend Origin is using "Cache-Control" or not?

If yes, can you please disable "Cache-Control" on the Origin and only use "Expires" ?

Refer : Cache-directive headers under "How caching works"

Cheers,

Kapil
KapilAnanth-MSFT 35,001 Reputation points Microsoft Employee

2023-02-03T10:46:56.65+00:00

@Anonymous

May I know if you got a chance to review my previous comment?

Please let me know if you are facing any challenges or if there are any follow-up questions, I shall be glad to address them.

Thanks,

Kapil