Exchange high availability namespace design and planning

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 about Exchange high availability namespace design and planning configuration.

Information Exchange high availability namespace design

Before you start, look at the Exchange Server course and install the first Exchange Server. By doing that, you will clearly understand how to install, configure, and manage Exchange Server.

When installing Exchange Server on-premises, it doesn’t matter which version you choose; 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.

Let’s have examples of what internal hostnames look like:

• .local
• .priv
• .internal
• .lan

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 cause problems
• Configuring Exchange Hybrid deployment will cause problems

Note: We recommend making use of a generic namespace. For example, mail.yourdomain.com.

In our example, we have an internal domain with the name exoip.local and external domain exoip.com. Therefore, we will configure the namespace as mail.exoip.com.

Exchange high availability namespace planning

An architecture view of Exchange high availability namespace is shown below in the diagram.

• The public DNS/External DNS zone 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.

If you have a multi-site (Site A and Site B), then an unbound model is an excellent choice, and it will look like the diagram below.

Configure Kemp load balancer

Install and configure Kemp load balancer with an IP address. After that, add both the Exchange Servers to the load balancer for HTTPS high availability.

Configure internal DNS for Exchange Server

Configure the DNS zones internally with Pinpoint DNS. Both these records are A records.

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 for Exchange Server.

Configure internal and external URL in Exchange Server

Configure the Exchange Server internal and external URLs with the same name. Almost all the URLs will have mail.exoip.com in the configuration. That’s because the AutoDiscover URL will be different.

Service	Internal and External URL
AutoDiscover	https://autodiscover.exoip.com/Autodiscover/Autodiscover.xml
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 for 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 four records for high availability.

Note: Always use a spam filter to protect your Exchange Server organization from incoming and outgoing spam. The one we recommend is the SpamBull cloud spam filter.

Record Type	TTL	DNS Name	Priority	Value
A	300	mail.exoip.com		73.122.35.127
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 for Exchange Server.

Conclusion

You learned about 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 in the future.

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