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I have this issue:
In order to upgrade MS Office from 2013 to 2016 I had to set-up autodiscover so Outlook 2016 can connect to the Exchange 2010.

Let's say this is my autodiscover URL:
https://autodiscover.example.com/Autodiscover/Autodiscover.xml

All DNS records are set properly in Cloudflare but I have consequently this issue:
The browser shows the error the above autodiscover page cannot be reached. When I press for 10! minutes every 5 seconds the Refresh button then - without having changed anything - suddenly the login form appears and then I can successfully authenticate and the expected Error 600 is shown because the request is wrong but the server replies.

Then, when I refresh again for couple of minutes the browser suddenly reports that the page cannot be reached again!

I got 6 email accounts and it took me 80! minutes till Outlook could successfully reconnect to all mailboxes.

The DNS record is set like this in Cloudflare: enter image description here

And now this: Checking the DNS records for the domain this is the result [I tried several online checking tools]:
enter image description here

Ok, Google helps and this is the explanation why the CNAME record is not shown:
https://community.cloudflare.com/t/cname-records-are-not-shown-in-a-cname-lookup/3393/2

My questions:

  1. Why do I get so many times that the autodiscover page cannot be reached?
  2. Can it be I have to change the DNS record [From CNAME to A?] because I use Cloudflare in order to fix the issue regarding <page cannot be reach> and <it can be reached>?
Peter VARGA
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  • Your first problem is that you are using a browser to troubleshoot autodiscover. Stop doing that and use Outlook. There debug commands in Outlook which allow you to test autodisover and it will display a very detailed breakdown of the autodiscover process. Follow this here then post back with the more detailed results https://docs.rackspace.com/docs/set-up-autodiscover-for-outlook#:~:text=Test%20Autodiscover%20functionality%20in%20Outlook&text=While%20Outlook%20is%20running%2C%20press,select%20Test%20E%2Dmail%20AutoConfiguration. Paste back the results from the test – Mucker Aug 28 '23 at 11:18
  • What do you mean Outlook doesn't open for 90 mins? Are you really saying that when a user launches Outlook, it LOADS for 90 mins, before you can use it? If yes, you have big problems. You should at least be able to open Outlook on a machine and the run the tests I said - even if you have to install Outlook on a fresh machine – Mucker Aug 29 '23 at 09:14
  • @Mucker I know that I have big problems, therefore I am asking here for help. As I wrote, the https://autodiscover.example/autodiscover/autodiscover.xml URL doesn't work reliably. I get lot of time-out's and until a "window" opens where the URL is accessible it takes up to 90 minutes for the 1st time. Once it could connect to all 6 mailboxes then Outlook starts properly. – Peter VARGA Aug 29 '23 at 09:28
  • ok that bit wasn't clear... you did say you had issues with URL, but your last comment implied an issue with Outlook itself which seems is not the cause. Well something else to consider is to remove this service from Cloudfare. The idea of cloudfare is cache web pages, but autodiscover this will only be detrmintal because CF will have to retrieve info EVERY time from your EX server. The issue could be cause BECAUSE of the caching. CF is bringing no benefit for this service and is likely detrmintal to it. I would remove this URL from it if I were you. See if that fixes it and let us know. – Mucker Aug 29 '23 at 09:36

2 Answers2

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The issue is probably Cloudfare. The idea of cloudfare is to cache web pages, but for autodiscover this will only be detrimental because CF will have to retrieve info EVERY time from your EX server. The issue could be BECAUSE of the caching. CF is bringing no benefit for this service and is likely detrimental to it. I would remove this URL from it if I were you.

Additional info from OP:

I was thinking that it maybe CF, but CF was acting just like a external name server. Removing the domains from CF was not an option. Due to the fact I am running my own SBS/Exchange I created on the SBS for these domains DNS-zones and added an A entry for autodiscover pointing directly to the Exchange.

Office 2016 is running only inside a Terminal Server which is connected to the domain, so there is indeed no need the DNS resolution is done by an external name server.

After these steps the issues immediately have gone. Strange, because CF was not proxying it, it was just returning the IP.

I think, it maybe also a firewall problem because CF returned the public IP address and I suspect my network administrator didn't configure it correctly.

Peter VARGA
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Mucker
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  • Glad to see it fixed it. So you mean you were using CF for it's DNS hosting only? I can see how adding an internal DNS record fixed your issue, but you have only bypassed the issue rather than solve it. By adding DNS locally, you machines resolve the DNS to the local PRIVATE IP address right? This is something called Split-Brain DNS. If you were try this externally you'd likely still have the sam issues as external machines will send the DNS queries to CF where the issue is. It does still sound like a caching issue tbf, but it will only affect external users now. Your phone won't work though – Mucker Aug 29 '23 at 13:01
  • You are totally right and I _know_ I did not fix the issue. Therefore I added my suspicious with the firewall. I am running the SBS/Exchange for my wife and me. So we can start here to ask if it really makes sense to run for 2 people such an infrastructure. I want to do it because I know where my data is and in **my special case** it's the cheapest solution. Yes, SBS resolves `autodiscover.example.com` to `10.10.50.201`. On the phone it's not a problem as the email clients don't use the `autodiscover` method & I also mentioned, that I use it inside a Terminal Server where the SBS is private.. – Peter VARGA Aug 29 '23 at 15:11
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If the Autodiscover URL or DNS records are configured correctly, have you tried switching to a different browser or clearing your cache to see if that helps?

Ivan Lv
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