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Emilio_Torres_2's avatar
Emilio_Torres_2
Historic F5 Account
Apr 23, 2014

Resolv::nslookup timeouts

Hi all,

 

I'm using resolv::lookup to validate if any of the DNS configured in a Pool has the "A" record configured when i receive a positive response back the response to the user and stop the irule execution. Everything looks that works fine, but our customer is asking which is the timeout that resolv::lookup handle when a DNS server is slow? i mean, how many time takes to "resolv::lookup" command decide that there is no a response from the DNS server ? how many seconds, miliseconds?

 

Thanks in advanced,

 

Emilio

 

application delivery
availability
BIG-IP DNS
devops
iRules
LTM
  • nitass's avatar
    nitass
    Icon for Employee rankEmployee
    Apr 23, 2014

    this is mine.

    [root@ve11a:Active:In Sync] config  tmsh list sys db one-line | grep tmm.resolv
sys db tmm.resolv.cachesize { value "8192" }
sys db tmm.resolv.retry { value "3" }
sys db tmm.resolv.timeout { value "5" }
  • Jordan_Self_149's avatar
    Jordan_Self_149
    Historic F5 Account
    Apr 23, 2014

    Hello Emilio,

     

    I believe the following DevCentral wiki answers your question.

     

    "By default, TMM will make up to 4 consecutive query attempts (1 original with 3 retries) with an individual query timeout of 5 seconds."

     

    https://devcentral.f5.com/wiki/irules.resolv__lookup.ashx

     

    Best Regards,

     

    Jordan

     

  • Emilio_Torres_2's avatar
    Emilio_Torres_2
    Historic F5 Account
    Apr 26, 2014

    Nitass and Jordan,

     

    Thanks a lot for your responses, are very useful and is now clear for me what could expect from this irule in case of slow DNS responses.

     

    Best regards,

     

    Emilio