DNS caching and limited nic failover

Normally NIC failover is accomplished via a virtual adaptor pointed to 2 physical adaptors. when this is not possible (flaky software, no software etc) Roughly the same thing can be accomplished with dns tweaks.

1) make sure the server has both nic adaptors set to static addresses that are properly registered in dns. check this with nslookup (servername) it should return 2 addresses.

2) set the dns cach limits on ALL clients (ie logon script)

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters]
"NegativeCacheTime"=dword:00000000
"NegativeSOACacheTime"=dword:00000000
"NetFailureCacheTime"=dword:00000000
"AdapterTimeoutCacheTime"=dword:00000000
"NetFailureErrorPopupLimit"=dword:00000000
"MaxCacheEntryTtlLimit"=dword:0000000a
"MaxSOACacheEntryTtlLimit"=dword:0000000a

the top 3 lines set the Negative dns cache time to 0 seconds. By default windows caches lookup failures which can cause some problems. if you have dns servers across a WAN link you may want to set this to 5-10 seconds.

the bottom 2 lines set the dns cache to 10 seconds (a in hex) try to find a balance between failover time and increased DNS traffic.

this will fail back when the original adaptor comes back on line.

I have tested it in a windows 2k active directory environment and it works.

Problem:
Looking for a way to set adaptor priority

More Info:
http://support.microsoft.com/default.aspx?scid=kb;en-us;245437