From Jim Harrison - Add this to your ISA TO DO List
Jim Harrison posted are very useful email on several lists in which he outlines 2 quick registry changes that you'll want to make to improve the performance of your ISA 2004 Server. Here's his text unedited:
- Tired of the ISA sending NetBT broadcasts when DNS lookups fail?
HKLM\SystemCurrentControlSet\Services\NetBT\Parameters NodeType, DWORD, 0x2
..will cure that.
By setting this to a value of 2, You’re telling Windows to limit its name lookup efforts to defined DNS and WINS servers.
As a result, Windows will no longer wait for NetBT broadcasts to fail before reporting a name lookup failure.
Can you say “faster lookup responses and therefore faster connections (or failures)”, boys and girls?
- MS05-019 fixed an ICMP MTU vulnerability that existed in Windows.
Because the ISA team was aware of this issue before ISA 2004 shipped, they opted to give you a “safe by default” configuration since they had no idea if or when the Windows issue might be fixed.
Unfortunately, it also has the unfortunate side effect of limiting Windows to 576-byte packets on all interfaces, reducing network efficiency
HKLM\SystemCurrentControlSet\Services\Tcpip\Parameters EnablePMTUDiscovery, DWORD, 0x0
..is what the ISA installer creates.
HKLM\SystemCurrentControlSet\Services\Tcpip\Parameters EnablePMTUDiscovery, DWORD, 0x1
..is what will remove this protection (or you can delete the “EnablePMTUDiscovery” value).
Both settings require a machine reboot to take effect.
Both settings will clean up your network traffic a bit.