hi There,

I have a general question, is that SRV record "_autodiscover._tcp.domain.com" is compulsory in public DNS in order to establish the autodiscover to work from Internet or is there any other way(such as with A record) of getting the autodiscover done? 

please note my question is only about outlook connecting from internet.

Please use ExRCA (bing/google it) and you will see that there are 3 more methods, and srv is the last one ;)

Hi,

Following information displays the fundamental order of operations for how the Outlook client locates the AutoDiscover service:
1. Client looks for the SCP object.
Trying to connect https://domain.com/autodiscover/autodiscover.xml
If failed. Trying to connect https://autodiscover.domain.com/autodiscover/autodiscover.xml
2. If all the predefined URLs failed, Outlook will try the HTTP redirect method.
Trying to connect http://autodiscover.domain.com/autodiscover/autodiscover.xml
3. If still failed, we can use DNS SRV lookup for _autodiscover._tcp.domain.com, then "mail.domain.com" returned. Outlook will ask permission from the user to continue with AutoDiscover to post to https://mail.domain.com/autodiscover/autodiscover.xml

More detailed information,please refer to the bleow link:

https://social.technet.microsoft.com/Forums/en-US/54bc6b17-9b60-46a4-9dad-584836d15a02/troubleshooting-and-introduction-for-exchange-20072010-autodiscover-details-about-test-email?forum=exchangesvrgeneral

Regards,

David 

Hi,

Following information displays the fundamental order of operations for how the Outlook client locates the AutoDiscover service:
1. Client looks for the SCP object.
Trying to connect https://domain.com/autodiscover/autodiscover.xml
If failed. Trying to connect https://autodiscover.domain.com/autodiscover/autodiscover.xml
2. If all the predefined URLs failed, Outlook will try the HTTP redirect method.
Trying to connect http://autodiscover.domain.com/autodiscover/autodiscover.xml
3. If still failed, we can use DNS SRV lookup for _autodiscover._tcp.domain.com, then "mail.domain.com" returned. Outlook will ask permission from the user to continue with AutoDiscover to post to https://mail.domain.com/autodiscover/autodiscover.xml

More detailed information,please refer to the bleow link:

https://social.technet.microsoft.com/Forums/en-US/54bc6b17-9b60-46a4-9dad-584836d15a02/troubleshooting-and-introduction-for-exchange-20072010-autodiscover-details-about-test-email?forum=exchangesvrgeneral

Regards,

David 

• Proposed as answer by David Wang_Microsoft contingent staff 6 hours 15 minutes ago

Hi David, 

I agree SRV record is not compulsory to utilize the auto discover functionality, however in my case the outlook clients are trying to connect with https://www.domainname.com/autodiscover/autodiscover.xml, this shouldn't be the URL that outlook should connect with. As because we have our company website running on a webserver with www.domainname.com, auto discover request failing as expected(first stage).

After the above failure it then tries https://autodiscover.domain.com/autodiscover.com which sucessfully connects to Exchange servers and also autodiscover works fine.

my worry is why clients are trying to connect to https://www.domainname.com/autodiscover/autodiscover.xml, which is very strange to me and i'm afraid may be this is causing by any misconfigurations in my infrastructure.

Please let me know your opinion.

Hi David, 

I agree SRV record is not compulsory to utilize the auto discover functionality, however in my case the outlook clients are trying to connect with https://www.domainname.com/autodiscover/autodiscover.xml, this shouldn't be the URL that outlook should connect with. As because we have our company website running on a webserver with www.domainname.com, auto discover request failing as expected(first stage).

After the above failure it then tries https://autodiscover.domain.com/autodiscover.com which sucessfully connects to Exchange servers and also autodiscover works fine.

my worry is why clients are trying to connect to https://www.domainname.com/autodiscover/autodiscover.xml, which is very strange to me and i'm afraid may be this is causing by any misconfigurations in my infrastructure.

Please let me know your opinion.

That's the way autodiscover works.  It first checks to see if its on the domain and if it can find some SCP records in DNS.  If it cant look that stuff up in DNS it then tries - www.domain.com/autodiscover/autodiscover.xml.  If that fails then it tries autodiscover.domain.com/autodiscover/autodiscover.xml.  You can see this also happen at testconnectivity.microsoft.com