Autodiscover flow in an exchange on premises environment non-active directory environment part 3#3 part 28#36

of 20 | Autodiscover flow in an Exchange on-Premises environment | non-Active
Directory environment| Part 3#3 | Part 28#36
Written by Eyal Doron | o365info.com | Copyright © 2012-2015
Autodiscover flow in an Exchange on-
Premises environment | non-Active
Directory environment| Part 3#3 | Part
28#36
The current article is the continuation of the previous article, in which we review the
Autodiscover flow that is implemented in Autodiscover flow in an Exchange on-
Premises environment | non-Active Directory environment, by using the Microsoft
web-based tool, the Microsoft Remote Connectivity Analyzer (ExRCA).
Autodiscover flow in an Exchange on-Premises environment |
non-Active Directory environment | The article series

The current article is the third article in a series of three articles.
The additional articles in the series are:
 Autodiscover flow in an Exchange on-Premises environment | non-Active
 Autodiscover flow in an Exchange on-Premises environment | non-Active
To be able to review each of the steps and each of the parts that include a specific
Autodiscover step, we will use the powerful tool- the Microsoft remote connectivity
analyzer.
The Microsoft remote connectivity analyzer includes many tabs and options. In our
specific scenario, we want to test Exchange on-Premises infrastructure. To be able
to implement the required test, we will choose the Exchange server tab, Microsoft
Office Outlook Connectivity test and then, the option of – Outlook Autodiscover.

Note – in case that you need to get more details about the Microsoft remote
connectivity analyzer web tool you can read the article –Microsoft Remote
Connectivity Analyzer (ExRCA) | Autodiscover troubleshooting tools | Part 2#4 |
Part 22#36
Scenario description
To demonstrate the Autodiscover workflow that is implemented, in a “non-Active
Directory environment” when using an Exchange on-Premises infrastructure, let’s
use the following scenario:

John is an organization’s user who needs to access his mailbox that is hosted on the
Exchange on-Premise server.
John is physically located on a public network and, for this reason, he cannot use
the Autodiscover process that is implemented in an Active Directory environment.
The John E-mail address is – john@o365info.com
John task is- creating a new Outlook mail profile that will enable him to connect his
mailbox. The Outlook profile will be based on the Outlook Anywhere service.
Note that the company has a public website that is published using the host
named-o365info.com

Analyzing the Autodiscover process by using ExRCA
Before we will “dive in” into the details let’s start from a High-level view of the
Autodiscover test results.
In the following screenshot, we can see that the Autodiscover processes complete
successfully.
By looking at the Autodiscover results reports structure, we can see that the “first
part” failed (did not complete successfully) but the second part (B section) was
successfully completed.
Note – Autodiscover flow will “contain” a couple of “steps failure” 99% of times but,
still ended as a successful process.
The second part (B section) includes the “high level” description of each of the five
Autodiscover steps that were implemented and documented in the result report
(we will review in details each of these steps in the next section).

Analyzing the Autodiscover process | Steps described
in details

Step 1/9: Attempting to resolve the host name o365info.com in
DNS
By default, Autodiscover client will try to locate a “potential Autodiscover Endpoint”,
by using a host name that was “extracted” from the recipient E-mail address.
Autodiscover client will use the “right part” of the recipient E-mail address that
includes the SMTP domain name.
In our scenario, the recipient E-mail address is – john@o365info.com
Based on this specific E-mail address; the Autodiscover client will create a DNS
query looking for an IP address of a host named – o365info.com
The “answer” of the DNS server, depend on the specific organization public server’s
and services infrastructure.
For example, most of the organizations have a public website and, most of the time,
the public domain name is “mapped” to the public IP of the website.
In our scenario, the DNS reply with a public IP address of the requested host name.
The IP that was provided by the DNS server doesn’t “belong” to an Exchange server
(Autodiscover Endpoint) but instead, this public IP address is assigned to a standard
web server.
Step 1/9: Analyzing the data from the ExRCA connectivity test
In the ExRCA result page, we can see the following information:

The ExRCA tests results start with an error message that the connection attempt to
the host named – o365info.com failed.
Attempting to test potential Autodiscover URL
https://o365info.com:443/Autodiscover/Autodiscover.xml
testing of this potential Autodiscover URL failed.
(We will get more details about the reason for the failure in the next section).
Note that when we look at the details of the workflow that was performed by the
Autodiscover client, we can see that some of the steps to complete successfully.
For example, the resolution step in which the Autodiscover client asks for the DNS
server the IP address of the host o365info.com complete successfully.
Attempting to resolve the host name o365info.com in DNS. The host name resolved
successfully. IP addresses returned: 104.28.12.85, 104.28.13.85
Step 2/9: Testing TCP port 443 on host o365info.com to ensure
it’s listening and open.
The Autodiscover client addresses the potential Autodiscover Endpoint, using the IP
address that he got in the former step.
The Autodiscover client will try to verify if the potential Autodiscover Endpoint is
listing on port 443 (HTTPS).
In our scenario, the HTTPS communication test fails because the “destination host”
doesn’t support HTTPS communication.

In the ExRCA result page, we can see the following information about the Testing
TCP port 443 on host o365info.com:
The specified port is either blocked, not listening, or not producing the expected
response. A network error occurred while communicating with the remote host.
Step 3/9: Attempting to resolve the host name
autodiscover.o365info.com in DNS
Because the communication attempt with the potential Autodiscover Endpoint
using the hostname o365info.com fails, Autodiscover client move to the next
method, in which Autodiscover client will look for a potential Autodiscover Endpoint
using the following naming scheme – autodiscover + <Recipient SMTP domain>

In our scenario, the recipient E-mail address is – john@o365info.com
Based on this specific E-mail address, the Autodiscover client will create a DNS
query looking for an IP address of a host named – autodiscover.o365info.com
In the ExRCA result page, we can see the following information about the
Attempting resolve the hostname o365info.com:
Attempting to resolve the host name autodiscover.o365info.com in DNS.
The host name resolved successfully. IP addresses returned: 212.25.80.239
Step 4/9: Testing TCP port 443 on host
autodiscover.o365info.com to ensure it’s listening and open.
The Autodiscover client, address the potential Autodiscover Endpoint using the IP
address that he got in the former step.
The Autodiscover client, will try to verify if the potential Autodiscover Endpoint is
listing on port 443 (HTTPS).

In our scenario, the HTTPS communication test succeeded, meaning that the
destination host (the Autodiscover Endpoint) supports HTTPS communication.
In the ExRCA result page, we can see the following information about the Testing
TCP port 443 on host autodiscover.o365info.com :
Testing TCP port 443 on host autodiscover.o365info.com to ensure it’s listening and
open. The port was opened successfully.
Step 5/9: Asking from the potential Autodiscover Endpoint to
provide a public server certificate
The Autodiscover client “assume” that the destination host is a “potential
Autodiscover Endpoint”, that can provide him the required Autodiscover
information.
Before the Autodiscover client will ask for the required information, he will have to
a successfully complete couple of steps.

The Autodiscover client need “to be sure” that the destination host is a reliabletrust
wordy.
To be able to trust the potential Autodiscover Endpoint, the Autodiscover client will
ask for the server to prove his identity by providing a valid public certificate.
In the ExRCA result page, we can see the following information about the step in
which the Autodiscover client asks for the potential Autodiscover Endpoint to
provide a public server certificate:
The Microsoft Connectivity Analyzer is attempting to obtain the SSL certificate from
remote server autodiscover.o365info.com on port 443.
The Microsoft Connectivity Analyzer successfully obtained the remote SSL
certificate.

Step 6/9: Testing the SSL certificate to make sure it’s valid
The certificate validation test which the Autodiscover client performs, includes
three different parts.
1. Validating the certificate name
The Autodiscover client addresses the potential Autodiscover Endpoint using the
host name –autodiscover.o365info.com
To be able to know that this is the “real host”, Autodiscover client will check if the
certificate includes the specified host name (autodiscover.o365info.com )
Note – this description is relevant to a scenario in which the server uses an SAN
certificate.
In case that the potential Autodiscover Endpoint uses a wildcard certificate, the
client will validate only the domain name (in our scenario, the domain name that
the client will validate is –o365info.com).
2. Validating the certificate trusts
The public certificate that the server provide was created by a CA (certificate
authority).
The Autodiscover client will need also to validate the CA certificate that provides the
server his certificate.
3. Verify that the certificate date is valid
The Autodiscover client will need to verify that the server certificate date is valid.
Note – In case that you want to read more detailed information about the subject of
Autodiscover, security mechanism and certificates, read the article – Autodiscover
process and Exchange security infrastructure | Part 20#36

1. Validating the certificate name
In the ExRCA result page, we can see the following information about the validation
test for the Autodiscover Endpoint name:
The certificate name was validated successfully.
Host name autodiscover.o365info.com was found in the Certificate Subject
Alternative Name entry.
2. Validating the certificate trust
test for the certificate trust:

Certificate trust is being validated. The certificate is trusted and all certificates are
present in the chain. The Microsoft Connectivity Analyzer is attempting to build
certificate chains for certificate CN=mail.o365info.com, OU=Domain Control
Validated, O=mail.o365info.com.
One or more certificate chains were constructed successfully.
3. Verify that the certificate date is valid
test for the certificate data:
Testing the certificate date to confirm the certificate is valid. Date validation passed.
The certificate hasn’t expired.
The certificate is valid. NotBefore = 1/26/2013 11:22:11 PM, NotAfter = 1/26/2015
11:22:11 PM
Step 7/9: Checking the IIS configuration for client certificate
authentication
The Autodiscover client checks if the destination host (the Autodiscover Endpoint)
needs a client certificate. A client certificate is a method in which the client can
prove his identity by providing a certificate.

The use of the client certificate is very rare and most of the time, the way that the
client use for “proof his identity” is by providing user credentials.
On the ExRCA result page, we can see the following information about the client
certificate authentication test:
Checking the IIS configuration for client certificate authentication. Client certificate
authentication wasn’t detected. Accept/Require Client Certificates isn’t configured.
Step 8/9: Providing user credentials
After the certificate validation test was successfully completed and, the
Autodiscover client can “trust” the destination host, the Autodiscover client will also
need to prove his identity.

The Autodiscover client will identify himself by providing user credentials”
(Username + password).
Note – the part of “providing user credentials “doesn’t appear in the ExRCA results.
Step 9/9: Attempting to send an Autodiscover POST request to
potential Autodiscover URLs
This is the final step in the Autodiscover journey.
After a successful compilation of all the steps, the Autodiscover client completes his
mission – getting the Autodiscover file.
The Autodiscover Endpoint, will generate the Autodiscover response that was
“customized” to the specific Autodiscover client that requires the information (John
in our scenario).

In the ExRCA result page, we can see the following information about the
Autodiscover response that was sent by the Exchange CAS server to the client:
Attempting to send an Autodiscover POST request to potential Autodiscover URLs.
The Microsoft Connectivity Analyzer successfully retrieved Autodiscover settings by
sending an Autodiscover POST.
The Microsoft Connectivity Analyzer is attempting to retrieve an XML Autodiscover
response from URL
https://autodiscover.o365info.com:443/Autodiscover/Autodiscover.xml for user
john@o365info.com . The Autodiscover XML response was successfully retrieved.
The Autodiscover response included tons of information.
We will not review each of the “sections” that include in the Autodiscover responds,

but just as an example, we can see a couple of details that include in the
Autodiscover respond file:
The Autodiscover Exchange provider
Exchange CAS server include a couple of Outlook providers.
The Autodiscover will include a dedicated section for each of this provider.
In our example, we took a screenshot from the part that include the information for
the EXCH provider – <Type>EXCH</Type>
Note – If you need more detailed information about the Exchange CAS server
Autodiscover provider read the article – The content of the Autodiscover server
response | Part 11#36
In the following screenshot, we can see that the Autodiscover response includes the
“private” or the “hidden name” of the Exchange CAS server that provide the
Autodiscover services –<Server>EX01.o365info.local</Server>
The Autodiscover response, includes a detailed information about each of the
available Exchange web services.
In the following example we can see the information about the available
services:<ASUrl>https://ex01.o365info.local/ews/exchange.asmx</ASUrl>
And about the Automatic reply (Out of office)
services:<OOFUrl>https://ex01.o365info.local/ews/exchange.asmx</OOFUrl>

Autodiscover flow in an exchange on premises environment non-active directory environment part 3#3 part 28#36

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Autodiscover flow in an exchange on premises environment non-active directory environment part 3#3 part 28#36