DNS records with exchange

im sure its an easy fix but how do i setup exchange and dns so when users are physically at the same location of the server they do not have to disconnect from the wireless network to get mail.
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Why would they have to disconnect from the wireless to get mail?

If you are asking how to setup split brain dns so a URL like mail.yourdomain.com points to an internal IP address:

Setup a Forward Lookup Zone of mail.yourdomain.com in DNS.  Set a static A record for the internal IP of your server.
In Exchange, make sure all internal and internal URLs for services point to the external address, for example http://mail.yourdomain.com.

More on that here:
avswaneyAuthor Commented:
I didn't explain it we'll enough.  I'm sorry
    The devices that have to disconnect are mobile.  Like iPhones iPads and tablets.  When I set those devices up I'm using the static IP address from the ISP for the mail server. That's why they have to disconnect to get there mail.
Ok so when they come into the office, they cannot get mail when connected to the wireless most likely because the firewall doesnt allow them to come back in the WAN port from the LAN side like that.  In other words it sounds like they disconnect from WiFi, get on 3G/4G from Verizon or AT&T or whomever their service is through, and then can get mail.

Is there a reason you are not using a URL rather than the IP address?
If you set them up with the IP address rather than a URL, DNS isnt affecting anything, you've effectively bypassed it.

Definitely read the above link, setup split brain DNS and then change the devices to use the URL of your mail server rather than the IP address.  I'm going to assume you have MX records already setup to point to your IP Address setup at the registrar, otherwise mail wouldnt be working at all.
avswaneyAuthor Commented:
So I could use webmail.domain.com URL on the devices if the correct DNS record is set.
Yes and no.
If you set it without pointing internal DNS to look to the internal IP, then it should still remain broken (assuming I am correct about the loopback being disallowed on the firewall.)

If you setup DNS to look internally for webmail.domain.com then yes it should work.
Test a phone on wifi by pointing it to the internal IP of the mail server first to be sure that is the issue.

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