The content of the Autodiscover server response | Part 11#36 5/5 (1) 18 min read

In the current article, we will review the subject of the Autodiscover response content.
The term – “Autodiscover response” relates to the Autodiscover information that the Exchange CAS server provides to his Autodiscover client.In this article, we will refer to the Exchange Server Autodiscover response content from the perspective of the three Outlook providers –EXPR, EXCH, and ExHTTP.

Article Series Table of content | Click to expand

Exchange and Autodiscover infrastructure | Article Series

Exchange Autodiscover – Article series – INDEX

Exchange and Autodiscover infrastructure | The building blocks

Autodiscover infrastructure | FQDN and URL address

Exchange Autodiscover flow in different environments

Autodiscover infrastructure | Exchange infrastructure and namespace convention

Exchange, Autodiscover and security infrastructure

Autodiscover Troubleshooting tools

Autodiscover major flow scenarios

Autodiscover flow in an Exchange on-Premises environment | non-Active Directory environment

Autodiscover flow in an Office 365 based environment

Autodiscover flow in an Exchange Hybrid environment

Exchange Stage migration and Autodiscover infrastructure

For most of us, the content of the Autodiscover response is a mystery and, most of the time we are not able to understand the complete meaning of this mystery.

Autodiscover response mysterious file

The purpose of the current article is to remove some of the fog that relates to the content of the Autodiscover Exchange CAS server response so; we will be able to get more information about the fascinating process of Autodiscover.

Also, to have the ability to solve the difficult problems that relate to the communication channel and the Autodiscover process that implemented between the Autodiscover client and the Exchange CAS server.

Autodiscover response

Q1: Question – what is the meaning of Autodiscover response?

A1: The Autodiscover response is the “answer” that the Exchange CAS server provides to his Autodiscover clients.

The Autodiscover information - Server Client module

A metaphor that we can use that will help us to understand the relationships that exist between Exchange server, and his Autodiscover client is a metaphor of a person that feeds his Children.

The Autodiscover client needs a well (Autodiscover information), and they address Exchange server asking him to feed them (providing the Autodiscover response).

Exchange server feeds his Outlook client using Outlook providers

Q2: How does the client (Outlook) know what are the required parameters that he needs to use for communicating with the Exchange server?

A2: The Exchange server provides all the required information to the Outlook client as part of Autodiscover response. The “Autodiscover answer”, include the essential information that relates to the different communication parameters.

The main advantage of the Autodiscover method is that there is no need for using a complex manual setting for configuring Outlook client to use the required parameters.

Instead, Outlook uses the Autodiscover protocol for locating the required Exchange server, and the Exchange server knows how to “Pack and ship” the information using the Autodiscover response to the Autodiscover client.

The Outlook configuration setting sent to Outlook Automatically by Exchange and Outlook client know how to use this information for an automatic creation of an Outlook mail profile.

Autodiscover information is used by Outlook client to plugin the appropriate Exchange interface

Q3: Who are the Exchange Autodiscover clients?

A3: The most prominent Autodiscover client that fully depends on the Exchange Autodiscover services is the Outlook, mail client.

Exchange Autodiscover information is relevant to Exchange mobile client (ActiveSync client) and also for the Exchange web client (OWA).

Exchange Autodiscover response

Q4: What are the building block or the major parts of the Autodiscover response?

A4: The Autodiscover response includes the following parts:

  1. Information about the available Exchange web service
  2. Information that is needed for Outlook mail client for creating a new mail profile
  3. Information about the communication parameters the Exchange “dictate” to the Outlook client. For example – the communication protocol, the authentication protocol, etc.

Autodiscover response content parts

Q5: Can you provide a detailed explanation for each of the parameters that included in the Exchange Autodiscover response?
A5:
The answer to this question is not so simple, and even to me, some of the content look like a “mysterious words”.
There are two main reasons for the phenomenon of this “mystery.”

1. Dynamic environment
The Exchange infrastructure is a very dynamic environment, each of the Exchange software updates adds the type of services or updates to the existing Exchange services.

These Exchange updates are “registered” in the Autodiscover file, and as long that the “client side” such as Outlook knows how to relate to this update, it’s OK.

2. Lack of documentation or a public information

When I sat down to write this article, I have searched for free articles that will include a detailed description about each of the data fields that appear in the Exchange Autodiscover response.

The result – there are very few articles about the subject of the Autodiscover response content and, regarding the Autodiscover “key” that I’m not familiar with, I could not find additional or meaningful information.

So what is my point?
My point is that despite the “mysterious parts” in the Autodiscover response file, there are many other parts that we can understand and use in a troubleshooting scenario.

Note – many times in the Autodiscover article series, I use the term “Autodiscover file”.
If we want to be more accurate, actually there is no such thing as an “Autodiscover file”.The Exchange server “answer” described as “Autodiscover response” and this “response” include the content which I describe as “Autodiscover file”.
Technically, it doesn’t matter much as long as it’s easier for us to look at the Exchange server response as a “file”.

The autodiscover.xml not so clear

The file format of the Autodiscover file

The information that delivered by the Exchange server to his mail client is based on an XML format.

The XML format is implemented by using XML tags and, the “data” that included between the XML tags.

Each of and “XML sentence” began with an opening XML tag and end with a closing XML tag (the close tag is defined by the slash forward character “/”).
The data or, the information, resides between this XML tag.

The underlying assumption is that the “client side”, the element that the request for the information knows what is the meaning of the XML tag and how to use the information that resides between this XML tag.

When the Outlook client gets the Autodiscover information that is provided by the Exchange server, the client knows or to “relate” to each of the XML tags.

In the following diagram, we can see an example of a “piece of information” that taken from a standard Autodiscover response.

Autodiscover information using XML tags

In our example, the XML tag – <EwsUrl> define the URL address of the element (the Exchange server) that provides EWS services. The Exchange server hostname who provides the EWS services is – mail.o365info.com and, the URL address of the Exchange web services are –
https://mail.o365info.com/EWS/Exchange.asmx

The “client” such as Outlook, need to know or “understand” what the Exchange EWS services and know how to access the specified URL when he needs the Exchange EWS services.

Types of Autodiscover requests

Autodiscover client addresses the Autodiscover Endpoint (Exchange server) asking for Autodiscover information.

In an Exchange environment, the “request” for Autodiscover information by the Autodiscover client can be implemented by using three types of format or standard:

  1. EWS Managed API
  2. SOAP Autodiscover
  3. POX Autodiscover

The more advanced or preferred Exchange interface is the SOAP Autodiscover and the EWS Managed API.

The “decision”, which interface to use, depends on the Exchange client that addresses the Exchange CAS server (Autodiscover Endpoint).

Exchange server can answer or provide the required information for each of this different type of client request.

The term “Exchange client” can relate to the mail client such as Outlook, mobile devices, other Exchange server or any “Exchange-aware application.”

The Exchange interfaces for providing Autodiscover services

An exchange mail client such as Outlook uses the SOAP Autodiscover interface or the POX Autodiscover interface for submitting a request for the Autodiscover information.

  • When mail client address Exchange CAS server asking for Autodiscover information, using the POX Autodiscover interface, the client request is for a file named – xml
  • When mail client address Exchange CAS server asking for Autodiscover information, using the SOAP Autodiscover interface, the client request is for file named – svc

The Autodiscover File name

Note – in this article series when describing the flow in which Autodiscover client request for Autodiscover information, we will use the autodiscover.xml naming convention for representing the Autodiscover client request for Autodiscover information.
In reality, the Autodiscover client request could also refer to the file named – autodiscover.svc

Exchange Outlook Providers

Exchange server needs to provide his client a detailed information about the Exchange infrastructure. The information that is needed for creating a new Outlook mail profile, the information that is needed for communicating with the Exchange server and information about the existing Exchange web services.

To make it even more complicated, the “set of details” that need to provide to the internal Outlook client is markedly different than the details that need to provide to external Outlook clients.

An Exchange server, know how to “pack and ship” the required information for Outlook client via the Autodiscover response.

The information divided into sections.

  • Some of the sections include relevant information for internal Outlook clients.
  • Some of the sections include relevant information for external Outlook clients.

Exchange server pack and ship the information via the Autodiscover response

The method in which the Exchange server divides the information into sections for the different type of Outlook client, meaning external versus internal Outlook clients, described as – Outlook providers.

Exchange Outlook providers

Outlook providers and Exchange server version

Exchange 2007\2010 server version supports two types of Outlook providers

  • The Autodiscover response section (Outlook Provider) that includes relevant information for internal Outlook clients described as – EXCH
  • The Autodiscover response section (Outlook Provider) that includes relevant information for external Outlook clients described as – EXPR

Exchange server version 2007 2010 - Outlook Providers

Exchange 2013 server version supports the “former” type of Outlook providers, meaning EXCH and EXPR and in addition, a new type of Outlook provider named – ExHTTP.

Two interesting things about the Exchange 2013 server ExHTTP Outlook provider

1. Identical “ExHTTP section” for internal + external Outlook clients

The Exchange 2013 Autodiscover response, include two sections named ExHTTP for external + internal Outlook client versus Exchange 2007/2010 that use the different naming convention for Outlook providers (EXCH for internal Outlook client and, EXPR for external Outlook client)

In case that you are wondering, how the Outlook client “understand” if the information is related to the internal Outlook client or the for the external Outlook client, the answer is that the first “ExHTTP section” is for internal Outlook clients and the second “ExHTTP section” is for external Outlook clients.

Exchange server version 2013 - Outlook Providers -01

2. The content of the “ExHTTP section”

Most of the “ExHTTP section” content, is inherited from the content that exists in the EXCH section and, from the content that exists in the EXPR.

Attached a quote from Microsoft article –

In Exchange 2007/2010, the way Outlook Anywhere implemented is that you had one namespace you could configure. In Exchange 2013, you have both an internal host name and an external host name. Think of it as having two sets of Outlook Anywhere settings, one for when you are connected to the corporate domain, and another for when you are not.

You will see this returned to the Outlook client in the Autodiscover response via what looks like a new provider, ExHTTP.

However, ExHTTP isn’t an actual provider, it is a calculated set of values from the EXCH (internal Outlook Anywhere) and EXPR (External Outlook Anywhere) settings. To correctly use these settings, the Outlook client must be patched to the appropriate levels (see the Exchange 2013 System Requirements for more information). Outlook will process the ExHTTP in order – internal first and external second.

[Source if information – Client Connectivity in an Exchange 2013 Coexistence Environment]

In the following diagram, we can see the logic of the Exchange Outlook providers.

Exchange 2013 server provides the “old Outlook providers” and the “new Outlook providers”.

The ExHTTP Outlook provider is used for external + internal Outlook client at the same time. The “secret” is that the first section of ExHTTP is aiming to internal Outlook clients and the second section of ExHTTP, is aiming to external Outlook clients

Exchange server version 2013 - Outlook Providers -02

In case that you want to view the Outlook provider whom a particular Exchange server provide, you can use the following PowerShell command

Get-OutlookProvider | Select Identity

Display Exchange Outlook providers using PowerShell

In the following diagram, we can see that the Exchange 2013 support the “former” Outlook providers, also, include a new type of Outlook provider named – ExHTTP

Exchange server 2013 versus Exchange 2007 2010 - Outlook Providers

Exchange Autodiscover response XML structure and content

The Exchange Autodiscover response is built by using a specific structure.

An example of a standard structure of an Autodiscover response (the “XML file”) that provided by the Exchange 2013 server presented in the following diagram.

The Autodiscover response XML file structure

Viewing the content of the Exchange Autodiscover response file

To be able to understand better the content of the Autodiscover response, we will use an example of Exchange 2013 Autodiscover response that located in environments that have the following characters:

The Exchange 2013 is a Public facing Exchange server, meaning, the Exchange server provides services to be internal + external mail clients.

The namespace infrastructure based on a “separation” between the internal namespace and the external\public namespace.

  • The internal namespace of the Exchange server is – o365info.local
  • The external namespace of the Exchange server is – o365info.com

Scenario description - Autodiscover response

In the following section, we will review some of the content that included in the Exchange Autodiscover response.

1. EXPR section – information for external Outlook clients

The XML information based on “block of information”.

The section of the EXPR (that is relevant to external Outlook clients) has a beginning and an end (number 1).

The EXPR section is built from a collection of XML tags

Each XML tag has also a “starting tag” and “Ending tag” (number 2).

The content that needs to be “read” by the client positioned between the XML tags (number 3).

The Exchange server provides to the Outlook client about his hostname (his identity). Outlook client will use this name for addressing the Exchange server (number 4).

Exchange server “inform” Outlook client what protocol he should use as a communication protocol. In our scenario, the communication protocol is SSL (number 5).

Autodiscover response – EXPR Outlook provider -01

Most of the Exchange Autodiscover response content includes information about the different Exchange web services and other Exchange services.

The information about the specific services is “presented” with the XML tag and the information about the host who provides the specific services + the URL address of the particular service included between the opening and the closing XML tag.

For example, The following XML tag appears in the EXPR section

<ASUrl>https://mail.o365info.com/EWS/Exchange.asmx</ASUrl>

  • Information about the Exchange availability services (Free\Busy time) is provided by using the XML tag – <ASUrl>
  • In our specific example, the Exchange host name who provides the Exchange availability services is – mail.o365info.com
  • The URL address that Outlook client need to use when he needs to “consume” Exchange availability services is – https://mail.o365info.com/EWS/Exchange.asmx

Note that the EXPR section is relevant to external Outlook clients. For this reason, the information about the services that the Exchange server provide will be based on the “public identity” of the Exchange server. In our scenario, the Exchange server “present himself” by using the host name – mail.o365info.com

In the following screenshot, we can see we can see an example of different Exchange services that offered to Outlook clients.

Note that Exchange provides different services using the same URL address.

For example, Exchange availability services represented by the XML tag – <ASUrl> and Exchange OOO (out of office) services, are represented by the XML tag – <OOFUrl> have identical URL address – https://mail.o365info.com/EWS/Exchange.asmx

The “yellow arrows” point Outlook various Exchange services that provided by using the same URL address (number 1).

An example of additional Exchange services could be:

  • OAB – the OAB stand for – Outlook offline address book. The XML tag <OABUrl>, inform the Outlook client about the URL address that they need to use when that need to access Exchange server and download a local copy of the Outlook offline address book. In our specific scenario, the URL address is – https://mail.o365info.com/OAB/45831dde-e32e-4a86-9263-86ce0df67038 (number 2).
  • ECP – the Exchange web management interface. The Autodiscover response includes a dedicated XML tag named – <EcpUrl> that “tell” Exchange web client such as OWA, what is the URL address that should be used when there is a need to access the Exchange web management. In our scenario, the URL address is – https://mail.o365info.com/ecp (number 3).

Autodiscover response – EXPR Outlook provider -02

2. EXCH section – information for internal Outlook clients

In the following screenshot, we can see we can see an example of the EXCH section.

This section is relevant to internal Outlook clients.
For this reason, the information about the services that the Exchange server provide will be based on the “private identity” of the Exchange server.
In our scenario, the Exchange server “present himself” by using the host name – exo1.o365info.local

Autodiscover response – EXCH Outlook provider -03

3. ExHTTP section – information for internal + external clients

As mentioned, Exchange 2013 server adds to the Autodiscover response file additional section that includes a new type of Outlook provider, the ExHTTP section.

In the following screenshot, we can see that the Autodiscover response includes two different sections of ExHTTP

The XML tag name which used for the two sections is identical.

  • The first ExHTTP section (number 1) includes information related to internal Outlook clients.
  • The second ExHTTP section (number 2) includes information related to external Outlook clients.

Autodiscover response – EXHTTP Outlook provider -04

4. WEB section – information for OWA clients

The Exchange Autodiscover response includes a dedicated section for WEBmail clients (OWA clients).

We can see that the information that provided to the WEBmail clients also includes reference to the subject of internal versus external clients.

Autodiscover response – web client information -05

Some examples for the content of the Autodiscover XML file

In case that you will have the desired to look at the content of a standard Exchange Autodiscover response, you will be amazed by the amount of the data.

As I have mentioned before, I’m not familiar with all the information and the XML Tags that appear in the Autodiscover response.

But, there are some “famous” XML Tags in the Autodiscover response that we should know about because they represent the most important and essentials Exchange web services.

In the following diagram, we can see an example for these “famous” XML Tags.

A little taste of the information that is provided in the Autodiscover response

By looking at the structure of the URL address we can use a couple of observations:

  • The access to Exchange EWS folder (Exchange Web Services) is implemented by requesting a “file named – asmx
  • The Exchange web services URL is represented by the XML Tag – <EwsUrl>
  • Different Exchange web services, are “represented” by the same URL address. For example- The URL address of the automatic reply (represented by the XML Tag – <OOFUrl> ) and the calendar sharing URL (represented by the XML Tag –<SharingUrl>) are “leading” or pointing to the same URL address.

Examples of Exchange web services that paper on the Autodiscover response.

  1. Offline address Book – the Exchange services that enable Outlook client to download a local copy of the Global address list is represented by the XML Tag – <OABUrl>. The URL address includes the file name that the client should ask for (in our example https://mail.o365info.com/OAB/45831dde-e32e-4a86-9263-86ce0df67038)
  2. Unified messaging – the URL address for the Exchange unified messaging is represented by the XML Tag <UMUrl>
  3. Exchange ECP – the ECP is the web address of the Exchange control panel. The ECP is used by web mail client (OWA) for managing and accessing their personal details.

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Summary
The content of the Autodiscover server response | Part 11#36
Article Name
The content of the Autodiscover server response | Part 11#36
Description
In the current article, we will review the subject of the Autodiscover response content. The term – “Autodiscover response” relates to the Autodiscover information that the Exchange CAS server provides to his Autodiscover client. In this article, we will relate to the Exchange Server Autodiscover response content from the perspective of the three Outlook providers –EXPR, EXCH, and ExHTTP.
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o365info.com
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3 Responses to “The content of the Autodiscover server response | Part 11#36”

  1. Wonderful article, Never thought that this kind of information is available on the net, Thanks for the efforts taken to create such a wonderful article, hats off to your explanation.

  2. Wonderful article, Never thought that this kind of information is available on the net, Thanks for the efforts taken to create such a wonderful article, hats off to your explanation.

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