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Use Smartphone for use on wifi network without the need to reconfigure

Glen KnightLead Techical Consultant


You have a bunch of iPhone users that all successfully synchronise with your exchange server from outside of your network using the mobile telephone network.  However, when you try to do the same using your internal wireless network synchronisation fails.

The reason for this is because your iPhones are configured to use the externally published exchange servers, for example which in turn is configured to use the external IP address of your router/firewall.

Most, if not all business class firewalls/routers are designed to block this type of looping from internal devices.


The way to resolve this is to configure your internal network to allow access to using an internal IP address.

The easiest way to do this is using your internal DNS servers by creating a forward lookup zone called and then creating a blank A record that is configured to use your Exchange servers internal IP address.

Using the DNS Console (Start> Administrative Tools> DNS) navigate to the Forward Lookup Zones, right click and select New Zone.  You will then be presented with the New Zone wizard.

Using the wizard select the following options:
Primary Zone
Store the zone in Active Directory
To all DNS Servers in the domain
Zone Name:
Allow only secure dynamic updates
Once the new zone has been created right click the zone and select New Host (A or AAAA).  In the dialogue box leave the name blank and in the IP Address section enter the internal IP address of the Exchange server.

If you are using multiple Exchange Servers then this IP address must be the Front End Server (if using Exchange 2003) or the Client Access Server (if using Exchange 2007 or 2010)


We can easily save the inclusive minutes of our data plans and save money by using our internal wireless networks to allow mobile devices to use our internal exchange servers (or any other service) without the need to reconfigure the mobile device.

This guide provides a simple solution to what can be an annoyance for your end users.

Written by Glen Knight (demazter) as part of a series of how-to articles.
Glen KnightLead Techical Consultant

Comments (12)

Dematzer was using that as an example, Alex. If you use mail.* use that in DNS to match your current setup.

There is already a forward looking A name with nothing but the internal server IP address. The domain is mydomain.local and we use for email. Any suggestions?
Sorry....posted to wrong open window.

thanks for the info jaredr80. not sure if anyone can provide more insight on this but here's some additional info. i added created the forward lookup zone and added the a record with the internal ip of the exchange server. i was able to send emails internally from the iphone and outlook, but emails to external addresses failed from the iphone and outlook. the messages just built up in the queue. so i deleted the dns entry and mail started to flow again. we use postini for spam and i think this is what may be causing this issue. the send connector for postini is should this be the name of the servername.domain.local?

And for the same scenario
But with a Dyndns ?  

That's not work .

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