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Exchange Autodiscover infrastructure – Introduction | Part 01#36

Autodiscover is one of the most important and essential components of the Microsoft Exchange server architecture but at the same time, one of the most “unknown” and “misunderstood” terms.

My primary goal is to “open a door” into the fascinating and exciting Exchange Autodiscover architecture.

When I decided that I want to write an article about the Exchange Autodiscover mechanism, I naively thought that I could cover this subject in a 3-5 article series.

The outcome result was a 36 article series on the subject of – Exchange Autodiscover service.
Although this number sound Impressive, I can assure you that many aspects and parts of the Autodiscover infrastructure that included in this Autodiscover article series.

Autodiscover is a magical “one word”, which includes inside of her, many different components, and parts.

The Exchange Autodiscover, have a linkage to almost all the Exchange architecture parts, in this way or another.

In the following “Autodiscover matrix” diagram, I try to illustrate the complexity of the term: Autodiscover.
All the terms, names, and infrastructures that appear within the matrix relates to the Exchange Autodiscover services and vice versa.

The Autodiscover matrix

The article content

The current article serves as a “first glimpse” at the Exchange Autodiscover infrastructure. In the present article, we will understand that we cannot really provide a “few words” explanations to the term – ”Autodiscover.”

We will review the major characters of the Exchange modern environment and see how the Exchange Autodiscover service “answers” the needs of the Exchange modern environment.

How to explain Autodiscover – Chicken and Egg syndrome

The biggest challenge that I had, when I sat down to write the Autodiscover series of articles was – the Chicken and Egg syndrome.

We cannot have a profound understanding of the Exchange architecture without a deep knowledge of the Exchange Autodiscover infrastructure, and we cannot have a thorough understanding of the Exchange Autodiscover infrastructure without an in-depth understanding of the Exchange architecture.

While reading the Autodiscover article series, you may experience a slight feeling of confusion because, many times I jump from one subject to other subjects that relates to the Exchange Autodiscover and then, jump back.

My point is – patience, sometimes the information looks a little mess-up and, not always you can easily connect the dots into a coherent picture.

In the end, the picture will become clearer!

What is the Exchange Autodiscover?

This question is like asking a ZEN question such as – What is the sound of one hand clapping?

The answer could never be a minor one because the term “Autodiscover” is one word that contains many meanings.

Most of the technical articles that relate to subjects of Exchange Autodiscover built on the underlying assumption that the reader is familiar with all the Autodiscover aspects, the different scenarios, the Autodiscover architecture and so on.

The simple truth is that although Autodiscover is one of an essential Exchange infrastructure that relates to almost all the Exchange essential services, for most of us, the Exchange Autodiscover is a “black box” and many times.

We don’t relay to understand or have a partial knowledge about – what is the Exchange Autodiscover service, what the Autodiscover does and, how to do the Autodiscover work.

If we want to define the essence of the Exchange Autodiscover services, we can say that the primary purpose of the Autodiscover mechanism is – to provide an easy and straightforward method for getting information about:

  1. Communication parameters – the communication channel between Exchange clients and the Exchange server, is based on a predefined parameter such as a specific type of authentication protocol, a particular kind of data encryption protocol, the communication protocol, and additional parameters.
  2. Information about specific Exchange services and the Exchange hosts who provide this service – Exchange infrastructure is a very rich environment that offers many types of different services to the Exchange clients.
    The Exchange client mission is – to find what are the available Exchange services and who are the Exchange hosts who provide this service.

Theoretically, we can create some kind of a configuration file that will include all the required information and will deliver to each of the Exchange clients, but the reality is much more complicated because of three main reasons.

1. Different Exchange clients

Different Exchange clients will need to use different configuration parameters. There could be many examples of the differences requirements and needs of the various Exchange clients. For example, ActiveSync Exchange clients will use different communication protocols and parameters vs. Exchange clients such as Outlook.

Another example is the Exchange server version – Outlook Exchange users whom their mailbox hosted on Exchange 2007 Mailbox server will use different communication parameters vs. Outlook Exchange users whom their mailbox hosted on Exchange 2013 Mailbox server.

2. The physical location of the Exchange clients

The communication protocols and parameters of Exchange client such as Outlook, are different in case that the Exchange client located in the internal organization’s network vs. a scenario in which the Outlook client located on a public network.

3. Dynamic environment

The information about the existing Exchange infrastructure is a “dynamic information” that affected by many different factors such as availability of Exchange Server: new Exchange servers who can provide a particular service, non-existing Exchange servers which removed, new Exchange services, etc.

The purpose of the Exchange Autodiscover architecture is:

  • Client side – automate the process of “recognizing” the specific Exchange servers
  • Server side – based on this Exchange client type, Exchange server provides the information that he needs in an automatic manner. The Exchange client doesn’t need a “predefined knowledge” about the Exchange infrastructure or need to use a manual configuration setting.

Autodiscover – the source for the information

Throughout the series of articles, we will review in details the concepts such as Exchange CAS server as a source for information, from what the information consists of and more.

To this point in time, we will be satisfied with a mere reference to the fact that the source for all of this “automation” is the Exchange server which holds the CAS server role.

The Autodiscover architecture based on a client side “detection” or “locating” mechanism in which the Exchange client uses a particular method for determining the Exchange CAS server who will provide the Autodiscover information.

Autodiscover different perspective

The term “Autodiscover” is “interpreted “differently by the Exchange client side vs. the Exchange server side perspective.

Autodiscover – the Exchange client side

From an Exchange client side perspective, the meaning of the term -”Autodiscover”, is:

  1. The method which is used by the Exchange client for, locating and connecting the “source of information” (an Exchange CAS server).
  2. The process in which the Exchange client gets the information from the “information provider” (an Exchange CAS server).
  3. Using the information (the Autodiscover information) for different purposes such as: creating an Outlook mail profile, locating Exchange web service, etc.

Exchange server side

From an Exchange server side perspective, the meaning of the term ”Autodiscover” is-

  1. The ability to gather and generate a specific information (Autodiscover information).
  2. The ability to provide the required information to his Exchange clients.

The Autodiscover clients

The term – “Autodiscover client” can be translated into many types of Exchange clients.

For example, the Autodiscover client can be a “standard Exchange mail client” such as Outlook or Mobile (ActiveSync) client.
Another “translation to the term – “Exchange client “could also be another Exchange server who needs to get information from a particular Exchange organization.

An example of this type of scenario could be a Hybrid configuration that implemented in an Office 365 environment in which the Exchange Online can consider as “Autodiscover client” that needs to locate Exchange on-Premises server resources and query this “Exchange on-Premises” resources for information.

To most “noticeable” Exchange mail client that which entirely relies on the Exchange Autodiscover service is the “Outlook mail client”.
There is another Autodiscover mail client such as Mobile (ActiveSync) clients, but most of the information and examples and the client protocol connectivity flow described will mainly relate to the Outlook, mail client.

The Autodiscover client\server concept

Exchange infrastructure is based upon a client\server module. The client addresses the “server” and asks for the server to provide him services such as accessing his mailbox, information services, Exchange web services and so on.

In the Exchange architecture, the “server side” is represented by the Exchange CAS server.

The Exchange client entirely depends on the Exchange server which holds the Exchange CAS server role.

The Autodiscover infrastructure is built “into” Exchange mail clients such as Outlook. The first word that every Outlook clients learn to say is – Autodiscover!

  • The Outlook Exchange client uses the Autodiscover mechanism for locating the required Exchange CAS server (Autodiscover Endpoint).
  • After the Exchange client manages to find and connect his Exchange CAS server, the Exchange client (Outlook) sends an “Autodiscover query,” for getting the required Autodiscover information (information about configuration settings and Exchange web services).

All that an Exchange CAS server wants to do is – “nourish” his clients, by providing them the Autodiscover information.

The Importance of the Autodiscover as an infrastructure in Exchange environment

We can relate to the Exchange Autodiscover as a “motherboard” that hosts or serves as an infrastructure, for all the “other Exchange parts.”

In other words, we cannot really understand the Exchange infrastructure without a profound understanding of the Exchange Autodiscover infrastructure.

Q: Why should I care so much about the Exchange Autodiscover service?

A: There are a couple of answers for this question.

1: Exchange Infrastructure: designing, planning, and deployment

The section which I describe as – design, planning, and deployment Exchange infrastructure” relates to many possible scenarios such as:

  • Building a new Exchange infrastructure from scratch.
  • Exchange coexistence environment – Upgrade existing Exchange infrastructure. A scenario in which we add a “new Exchange server version” into existing Exchange infrastructure.
  • Implementing a migration project in which, we need to migrate the existing Exchange on-Premises server mail infrastructure to the “cloud” (Exchange Online) and connect users to their “cloud mailboxes”.
  • Implementing and building an Exchange Hybrid environment which combines the Exchange on-Premises infrastructure + the cloud (Exchange Online) infrastructure.
Why is it so important to know about the Exchange Autodiscover services-01

The common denominator for all of these different “Exchange scenarios” is that to be able to complete successfully the task of – “designing, planning, and deployment” different scenarios in the Exchange environment, we will need a thorough understanding of each of the various Exchange components. Especially, the Exchange Autodiscover infrastructure that relates and “touches” each of the different Exchange infrastructure parts.

2: Exchange infrastructure – troubleshooting scenarios

Equates to a good doctor, that should know the human body, the way to “heal” problem in Exchange infrastructure is – to know and understand what the Exchange different parts are, what is the purpose of these “Exchange parts,” how do the “parts” relate to each other, what is the relationships between these Exchange parts and so on.

Miss configurations and problems with the Autodiscover infrastructure, could lead to many of the common “Exchange troubleshooting scenarios” such as:

2.1 The classic troubleshooting scenario: cannot create a new Outlook profile.

One of the most traditional troubleshooting scenarios is a scene that described by users as: “cannot connect to Exchange” or in other words- It cannot create a new Outlook mail profile.

The answer of – “what is the cause that prevents the user to create the required new Outlook mail profile”, can relate to many factors and one of the major or prominent factors is – miss configuration or missing Autodiscover settings.

Even if we are sure, that the case for the problem is – miss configuration of the Autodiscover configuration, before we can provide the answer or the solution to the problem, we will have to know what is the exact Exchange infrastructure. Each of the different Exchange infrastructures have different charters and different “parts”, that we will need to check and verify.

For example, the process of creating a new Outlook mail profile on the internal network is implemented in a different way from the scenario, in which the user tries to create a new Outlook mail profile from a public network.

In a Hybrid environment, there is a significant difference between users who connect to their Exchange on-Premises server mailboxes vs. Exchange users whose mailboxes is hosted on Exchange Online.

2.2 Exchange hybrid environment

In this section, we can mention multiple troubleshooting scenario that relates to the “relationships” that exists between the Exchange on-premises infrastructure and the “cloud mail infrastructure” (Exchange Online).

For example – in the Hybrid environment, many of the services that are “shared” between the Exchange on-Premise server and the Exchange Online, depend on the Autodiscover infrastructure.
A miss configuration of the Autodiscover infrastructure, can and will lead to many possible problems beginning with – availability services (cannot see Free/Busy time), move mailbox (cannot migrate a mailbox to Exchange Online) and much more.

In the following diagram, we can see a simple classification of the “Exchange troubleshooting scenario” that could be related to the Autodiscover infrastructure.

Why is it so important to know about the Exchange Autodiscover services-02

3: Plain curiosity | Autodiscover as black box

We are living in the generation of fast food.
Everyone wants it quick and now!

This is me “lecturing” about the good all days.
I know many Exchange administrators and Exchange implements, which do what they do, without really understand what they do.

Most of the time, the prevailing view is – “we will cross that bridge when we get there.”
For example, in the case of a problem or error, I will “google it” and probably find the solution.

My world view dictates that there is no way to be an “Exchange Professional” without deeply understanding the internal and the gates of the Exchange architecture.

Yes, the word “curiosity” is not a dirty word!

Most of the time, we are living on a very flat level of information.
The formula is as follows: I have a problem ==>I need a solution==>I look for a solution ==>I find the solution ==>I implement the solution ==>the problem was solved = everybody happy!

However, 99% of the time, we are not willing to spend the time to understand the “inside” the “under the hood” of a specific infrastructure such as the Exchange and Autodiscover infrastructure, in our case.

The o365info Team

The o365info Team

This article was written by our team of experienced IT architects, consultants, and engineers.

This Post Has 6 Comments

  1. Great Great Work!! I wish, i could have find this article earlier. I barely read but you made me read all the article. I wish my teacher like you..

  2. Thank you for the blog, For beginners like me your blog is the right place to start about Autodiscover understanding !!

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