Exchange Autodiscover infrastructure - Introduction | Part 01#36

Page 1 of 30 | Exchange Autodiscover infrastructure - Introduction | Part 01#36

Written by Eyal Doron | o365info.com | Copyright © 2012-2015

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” term.

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My main goal is to “open a door” into the fascinating and interesting 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 are included in this Autodiscover

article series.

Autodiscover is like 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.




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The article content

The current article serves as a “first glimpse” at the Exchange Autodiscover

infrastructure. In the current 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

profound understanding of the Exchange Autodiscover infrastructure, and we

cannot have a profound understanding of the Exchange Autodiscover

infrastructure without a profound 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.

At the end, the picture will become clearer!

The Autodiscover article series

The challenge that I was facing was – how to “wrap” all of this huge amount of

terms, concepts, technologies, infrastructure and so into a one coherent digestible

content?






The answer for this question is – the current Autodiscover article series.






In case that the first question that appears in your mind is:

”What the f… I need to read so many tedious and boring articles?”

And the second question is – “Why this strange guy does not find himself a life?”

The answer to the first question is that: you don’t have to read each of the articles

in the “Autodiscover article series” but because each of the articles deals with a

different aspect of Autodiscover and if you want to “understand well” the

Autodiscover infrastructure, you can gain from reading the complete Autodiscover

article series.

Regarding the second question about the “life of the guy who writes the article.”

The answer is that: I have a life, but at the same time, I found the subject of

“Exchange Autodiscover” interesting for a fascinating process.






Many times I have felt frustration from the lack of a simple explanation of the

Exchange Autodiscover service and many times; I got confused from all the

different aspects of Exchange Autodiscover infrastructure.

So my “revenge” was – the “Autodiscover article series.”






Voltaire once said, “I do not agree with what you have to say, but I’ll defend to the

death your right to say it”

My paraphrase for this sentence is – I’m willing to spend a lot of efforts for

providing information on the Exchange Autodiscover infrastructure and knowing

that probably, very few people actually read the information.






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 simple 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 basic 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 do the

Autodiscover works.






If we want to define the essence of the Exchange Autodiscover services, we can say

that the main purpose of the Autodiscover mechanism is – to provide an easy and

simple 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 specific type 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 be delivered 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

different Exchange clients. For example, ActiveSync Exchange clients will use

different communication protocols and parameters versus, Exchange clients such

as Outlook.

Another example is the Exchange server version – Outlook Exchange users whom

their mailbox is hosted on Exchange 2007 Mailbox server will use different

communication parameters versus Outlook Exchange users whom their mailbox is

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 is located in the internal organization’s

network versus a scenario in which the Outlook client is 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 specific service, non-existing

Exchange servers who were 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 simple reference to the fact that the

source for all of this “automation” is the Exchange server who holds the CAS server

role.






The Autodiscover architecture is based on a client side “detection” or “locating”

mechanism in which the Exchange client uses a specific method for locating the

Exchange CAS server who will provide the Autodiscover information.






Autodiscover different perspective

The term “Autodiscover” is “interpreted “differently by the Exchange client side

versus 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 be also another Exchange

server who needs to get information from a specific Exchange organization.

An example for this type of scenario could be a Hybrid configuration that is

implemented in an Office 365 environment in which the Exchange Online can be

considered 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 fully 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 ask 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, totally depends on the Exchange server who 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 locate 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 about 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: designing, planning and deployment Exchange

infrastructure” relates to many passable 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.






The common denominator for all of these different “Exchange scenarios” is that to

be able to successfully complete the task of – “designing, planning and deployment”

different scenarios in the Exchange environment, we will need a thorough

understanding of each of the different Exchange components and 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 classic troubleshooting scenarios, is a scenario 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 settings, before we can provide the answer or the solution, for the

problem, we will have to know what is the exact Exchange infrastructure because,

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 in the internal

network, is implemented in a different way from the scenario, in which the user

tries to create a new Outlook mail profile form a public network.

In a Hybrid environment, there is a big difference between users who connect to

their Exchange on-Premises server mailboxes verse Exchange users whom their

mailbox is hosted on the Exchange Online.

2.2 Exchange hybrid environment

In this section, we can mention multiple of 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

passable problems beginning with – availability services (cannot see Free/Busy

time), move mailbox (cannot migrate a mailbox to Exchange Online) and many

more.

In the following diagram, we can see a simple classification of the “Exchange

troubleshooting scenario” that could be related to the Autodiscover infrastructure.






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 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 relay understand

the “inside” the “under the hood” of a specific infrastructure such as the Exchange

and Autodiscover infrastructure, in our case.









Documents

Exchange Autodiscover infrastructure - Introduction | Part 01#36