Server 2008 Auto-tune
The scenario: one of my clients has a Windows Server 2008box with Exchange 2007SP1. Random domains where not being sent to with error “451 4.4.0 DNS query failed” coming up in the Exchange Queue Viewer. Taz and myself troubleshot this over several days, looking at DNS Configuration, Exchange Configuration, and SonicWALL Configuration with no luck resolving the issue. So I made the call into Microsoft Tech Support, where over the course of two more days and 3 or 4 calls in which we went through the majority of the troubleshooting Taz and I had already done we finally found the issue was with Auto-tuning.
“Auto-tuning is a feature that was introduced with Windows Vista and Windows Server 2008 in order to optimize TCP throughput. The problem is that some network devices do not support these features (most Cisco Firewall devices, SonicWALL Firewall, Check Point Firewall, some NG R55 routers, some Netgear routers), which can make things slower (Rui Silva).”
The link below will walk you through how to disable auto-tuning.
This client has a SonicWALL Firewall and Microsoft was pointing at that possibly being the cause due to the output of the telnet sessions into the “problem domain” email servers. But, As stated above the issue was completely resolved once the Auto-tuning feature was disabled on the NIC. This leads me to the common issue I find with companies that make product features that are not supported by a significant amount appliance manufacturers. In the IT industry we see this regularly and we use work arounds or in this case turn off features. But, should we really have to? I suppose we can see it as job security but, isn’t good technology suppose to make it easier to manage, our business proccesses, networks, lives, etc? This will be the question as long as there are varied technlogies and companies. We as IT professionals just have to keep up the fight to make it work and make it better.