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Apr 28, 2020

2 TTL related registry on Windows client OS

1. Maximum time a client will cache positive results regardless what TTL a record holds:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Dnscache\Parameters\MaxCacheEntryTtlLimit

Note: A record will be cache on client for the period specified in


  • record TTL or
  • above registry value, whichever is less. 


2. When register its own record, the TTL sent to DNS server:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\DefaultRegistrationTTL


See Also


Apr 2, 2020

DNS Zone intervals - mapping values in Windows GUI to nslookup result for SOA record

DNS TTL 
See above, click to see enlarge picture.

This is a screenshot of SOA record.

What the intervals are:


  • (Most important one) Minimum default TTL: Default TTL for all records in the zone that don't have their own TTL defined during creation. This parameter is also used as TTL of negative cache
  • TTL : TTL for the SOA record itself
  • Refresh - This is how often (in seconds) the slave name servers check with the primary name server to see if any changes have been made to the zone
  • Retry - This is the time (in seconds) a slave (secondary) DNS server waits before retrying a failed zone transfer
  • Expires  - Indicates when the zone data is no longer authoritative - time counted from the point when slave loses contact with master. Applies to Slaves or Secondary servers only. When this expires, slave will no longer respond to queries
Update #1: Regarding negative caching, it is lesser of  Minimum Default TTL, SOA TTL, and 15min (defined in MaxNegativeTTL,  can be viewed with powershell cmdlet get-dnsservercache)

Update #2: One can set different values on SOA TTL and Minimum Default TTL, but Windows will set both to same value, whichever is smaller. Tested on Windows 2016

Nov 26, 2018

OS WMI Filter - OS version values

Version attribute Windows release
NE Any
95 Windows 95
98 Windows 98
ME Windows Millennium Edition
NT Windows NT operating system
2K Windows 2000 operating system
XP Windows XP
2K3 Windows Server 2003
2K3R2 Windows Server 2003 R2
VISTA Windows Vista
Version attribute Windows release
2K8 Windows Server 2008
WIN7 Windows 7
2K8R2 Windows Server 2008 R2
WIN8 Windows 8
WIN8S Windows Server 2012
WINBLUE Windows 8.1
WINBLUESRV Windows Server 2012 R2
WINTHRESHOLD Windows 10
WINTHRESHOLDSRV Windows Server 2016, Windows Server operating system, Windows Server 2019