Apple Mac computers lose connectivity to on-premise Exchange server

Every day we experienced many of our Macs losing their connection to the mail server which happened to be a Microsoft SBS 2008 server. For many months the solution was to connect to the public wireless connection that was OK for the users but it was just a workaround. Connectivity would be sporadic and having the Macs connected to the LAN over the wire and to the public wireless connection wasn’t a good long term solution.

After much troubleshooting I figured out that the configuration of their DNS and DHCP servers was incorrect. Research and testing revealed that Macs use Autodiscover to connect to the Exchange server. Internal DNS didn’t have the autodiscover records required by internal Exchange clients. And it didn’t matter what client – Entourage, Apple Mail, Outlook for Mac – they all lost connectivity quite often and a random times. Once was resolved but adding the proper records there was one other problem.

DHCP was configured to assigned the SBS server AND and external DNS server for DNS. Once that was rectified by setting DHCP to assign just the SBS server as the DNS server and running DNS Bench to determine the fastest DNS servers for the office and setting them as the forwarders, the Macs maintained stable connectivity to the Exchange server. Finally!

Why was this the case? The Macs need Autodiscover records to be set up correctly in DNS. That’s why connecting over public wireless connection worked. The external DNS servers had Autodiscover records set up correctly for external clients. Luckily this worked for their environment as a band-aid. When the internal one wasn’t configured correctly the Macs could never connect to the Exchange server using the internal DNS server to resolve hostnames.

Why was it sporadic? I chalk it up to the sometimes slow DNS name resolution of the SBS server. If it didn’t respond quick enough, it would force the Macs to use the external DNS server for name resolution and would work, but if the SBS server did respond in time, they would lose connectivity.

So fixing both was necessary – DHCP to only assign the SBS server as the internal DNS server and for DNS to be configured with the correct Autodiscover records.

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Is Windows or Mac slow, getting pop-ups, seeing too many ads, or is it freezing?

You probably have some form of malware. I consider malware to be software that causes your computer to act funny when you know the hardware is in good working order. Whenever I get reports that a person’s computer is suddenly doing things out of the norm, I immediately suspect malware as the cause. If it boots up into safe mode and acts like it should, then that’s a confirmation something is wrong on the software side of things.

If it still acts shows symptoms in safe mode then I may be some other problem. It could be a bad hard drive, motherboard, memory, or even malware that’s embedded itself in the lower levels of the operating system. A hardware diagnostics will more than likely tell us if it’s hardware. Most big name manufacturers include diagnostics software. You just have to find out how to get to it. In most cases it’s in the form of interrupting the normal boot up process with an F-key. Those keys at the top of your keyboard – F1 through F12, usually. If that comes back with everything passing, then you have malware.

If a system restore doesn’t rid your computer of the malware symptoms, I have three anti-malware tools that I use often in situations like these. Other techs have theirs and there are several out there. Here are the tools I use.

1. Kaspersky’s TDSSKiller

2. Malwarebytes

3. ComboFix

All are free to download and use. I usually run Malwarebytes first. Nine times out of 10 it’ll find what’s infected your computer. If problems still persist then I run TDSSKiller and ComboFix.

While Malwarebytes is scanning away, I’ll do couple other things.

I’ll check add/remove programs and see if there are any recently installed programs. If they look suspicious, I just remove them. If I’m not sure, I ask the owner or user if they’re familiar with and use the programs in question. If not then it’s removed. I find a lot of coupon or shopping applications as well as so-called “tune-up” programs that aren’t really viruses but cause the computer to run really slow. These are usually culprits for slowness and freezing problems. If you downloaded freeware from an unknown site and right afterwards the computer started acting up, then guess what, you probably got a Trojan malware.

It doesn’t really matter how you got malware. By virtue of being connected to the internet, you are prone to get some malware sometime. The good news is that you can get rid of them most of the time. Even the dreaded CryptoLocker. The way to remove it that worked for me several times is this. Google how to remove it manually – seriously. There are steps you can follow. Follow them. Run a Malwarebytes and ComboFix scan. You may get some message that CryptoLocker has been removed or tampered with or something like that and that your files are still locked and you still need to pay to unlock them. You won’t be able to open any files. Before paying the ransom try this. Create a brand new user profile. I don’t guarantee it’ll work for everyone but it’s worth a shot.

Running these free malware removal tools is free and easy. If you feel like you might have malware, try using them. Other tools that are free to download and use are SuperAntiSpyware, Spybot Search and Destroy, Avast, and Ad-Aware by Lavasoft. Malware is a fact of life in the connected world but with diligence and knowledge as well as these free malware removal tools, you can get your computer back to normal in no time.

What about Apple’s Macs?

Believe it or not, there are malware programs directed at you too! Don’t worry, big name antimalware companies have products for you. There are a couple free ones as well. Sophos Free and ClamXav are two I’m familiar with.