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Level 7

DNS Monitor - TCP

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When using the Application Performance Monitor to monitor TCP port 53 on several Windows 2003 R2 Servers several servers show the status as down because "The return code is different than expected."


 


 


 An ideas?

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Level 13

That message occurs when the response from the DNS server has a return code that is not 0 (success).  The DNS monitor does an ANAME query for "a.root-servers.net".  If the DNS server's response is not valid or the return code is not success (0) then the monitor fails.

 
 

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Level 13

That message occurs when the response from the DNS server has a return code that is not 0 (success).  The DNS monitor does an ANAME query for "a.root-servers.net".  If the DNS server's response is not valid or the return code is not success (0) then the monitor fails.

 
 

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Spot on, once the DNS servers had access to "a.root-servers.net" the DNS servers showed as up

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Can that be changed to query for a custom ANAME?

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 No

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Any chance this will be customizable in the future? Or is there another way to monitor DNS response other than just an open port check on 53?

Having this hard-coded limits use for monitoring external DNS servers as they should be set to Disable Recursion as a best practice to prevent DOS attacks.

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Yes I'd also like to insert a custom DNS entry when testing for DNS services on our servers.

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 We're hoping (although not promising) to deliver this functionality in APM 2.0.  When is 2.0, you're about to ask?  Q3-ish.

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OK, Thanks for the info.

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