Why in SBS 2008 after a short period DNS stopped and needed a reboot?

For a permanent work around, the MaxCacheTTL value needs to be changed to a value larger than the TLD TTL (Default value is 1 day, maximum value is 30 days). On SBS2008 there is no negative impact since this is the TTL for the cache of Resource Records. This is just the maximum value that it will be stored on DNS server. If the actual TTL is shorter, the

shorter value will be used.

1. Start Registry Editor (Regedit.exe).

2. Locate the following registry key:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS\Parameters
3. On the Edit menu, click New, click DWORD (32-bit) Value , and then add the following value:
   Value: MaxCacheTtl
   Data Type: DWORD
   Data value: 0x69780 (432000 in decimal = 5 days)

4. Click OK .
5. Quit Registry Editor.
6. Restart the DNS server.

As an extra precaution, clear the DNS resolver cache using

IPCONFIG /FlushDNS

After the change, the server should be monitored to check if the issue occurs again. Since this value won’t affect the normal behavior on SBS2008, we can increase this value to a larger value if the issue persists.

Pasted from <http://serverfault.com/questions/98999/sbs-2008-dns-stops-working-after-1-day-for-uk-eu-and-some-other-tlds-outside-u>