Saturday, January 31, 2009

RecursionTimeout Registry Key

This reg key determines the maximum time a dns server is allowed to do recursive query to remote servers repeatedly at regular intervals for resolving NS queries. i.e, If the DNS server does not receive a response for a recursive query, the server repeats the query at intervals as specified by the value of the registry key RecursionRetry. If the server does not receive a response before the value of RecursionTimeout expires.
Key Name: RecursionTimeout
Default: NoKey (Timeout is 15 seconds)
Functionaliry: timeout of DNS server to give up recursive query.
Location: "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DNS

By default, the RecursionTimeout is 15 seconds. But can be changed by editing the registry as shown below (assuem the time to be set is 200 seconds)
reg add "HKLM\SYSTEM\CurrentControlSet\Services\DNS\Parameters" /v RecursionTimeout /t reg_dword /d 200

Note: 1. changes to key done through reg add will be effective only after restarting the server
2. default 15 seconds is enough for most of the scenarios unless the dns server is on very low speed link.
3. if RecursionTimeout key is deleted, does not exist is zero, the DNS server timeouts after 15 seconds.


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