You want to create mailboxes in Exchange Online and use Office 365. Before you can…
An Exchange Server is already up and running in the organization. Before installing a second Exchange Server, it’s good to go to the drawing board. Exchange high availability namespace design and planning is by far the most crucial task. Take your time, and write the topology before deploying. In this article, you will learn Exchange high availability namespace design and planning configuration.
Table of contents
Information Exchange high availability namespace design
Before you start, look at the install Exchange Server course and install the first Exchange Server. You will have a clear understanding of how to install, configure, and maintain Exchange Server.
When installing Exchange Server on-premises, it doesn’t matter which version, this can be Exchange 2010/2013/2016/2019, the internal URLs match the fully qualified domain name (FQDN) of the Exchange Server. This design is by default. Examples how internal hostname look like are .local, .lan, or .internal.
You are asking for trouble if you proceed like this, for example:
- You can’t buy a third-party certificate based on the internal FQDN URLs.
- Autodiscover certificate warnings and issues when connecting with clients.
- You can’t load balance between multiple Exchange Servers with an internal FDQN.
- Adding another Exchange Server in the environment will give problems.
- Configuring Exchange hybrid deployment will give problems.
We recommend making use of a generic namespace, for example mail.yourdomain.com.
We have an internal domain named exoip.local and an external domain exoip.com. In my example, we will configure the namespace mail.exoip.com.
Exchange high availability namespace planning
An architecture view of Exchange high availability namespace is shown below in the topology.
- The public DNS / External DNS will have a mail.exoip.com record that resolves to the firewall or router’s public IP address. It will then NAT any external connections to the load balancer internal IP.
- The Internal DNS zone will have a mail.exoip.com record that resolves to the load balancer internal IP address.
Configure Kemp load balancer
Configure internal DNS Exchange Server
Configure the DNS zones internally with Pinpoint DNS. Both the records that we are going to add will look like the following.
Record Type DNS Name Internal IP Address
----------- -------- -------------------
A mail.exoip.com 192.168.1.54
A autodiscover.exoip.com 192.168.1.54
Read the article Configure internal DNS Exchange Server.
Configure internal and external URL in Exchange Server
We will configure the internal and external URLs with the same name. Almost all the URLs will have the mail.exoip.com in the configuration. That’s because the AutoDiscover URL will be different.
Service Internal and External URL
Exchange Control Panel https://mail.exoip.com/ecp
Exchange Web Services https://mail.exoip.com/EWS/Exchange.asmx
Exchange ActiveSync https://mail.exoip.com/Microsoft-Server-ActiveSync
Offline Address Book https://mail.exoip.com/OAB
Outlook Web App https://mail.exoip.com/owa
MAPI over HTTP https://mail.exoip.com/mapi
Outlook Anywhere mail.exoip.com
Read the article Configure Internal and External URL in Exchange Server.
Configure external DNS Exchange Server
There are six records that we are going to add to the public DNS. These are the A record, CNAME record, and MX record. The MX record will have 4 records for high availability.
Record Type TTL DNS Name Priority Value
----------- --- -------- -------- -----
A 300 mail.exoip.com 184.108.40.206
CNAME 300 autodiscover.exoip.com mail.exoip.com.
MX 300 @ 10 mx1.spambull.com.
MX 300 @ 20 mx2.spambull.com.
MX 300 @ 30 mx3.spambull.com.
MX 300 @ 40 mx4.spambull.com.
Read the article Configure external DNS Exchange Server.
This article is part of the course Exchange Server high availability.
In this article, you learned Exchange high availability namespace design and planning best practices. This is a setup for multiple Exchange Servers in a single site. Please pay close attention to the namespace design and plan it accordingly to avoid problems later on.
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