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Brant_Davis's avatar
Brant_Davis
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Oct 12, 2018

DNS Issues with Devices in Sync Group

I recently configured F5's DNS between some test DNS devices in two datacenters and trying to do a primary/standby datacenter configuration. The configuration is two virtual big-ip appliances in each datacenter running both DNS and LTM. I have configured a test virtual server in both datacenters and have DNS all configured. In total there are four DNS devices, two in each datacenter. They are all configured in a sync group. However I am only able to get a DNS reponse for the wide IP from the two DNS devices in the primary datacenter. The two DNS devices in the standby datacenter timeout when I try to lookup the record for the wide IP. Is this normal behavior?

 

application delivery
BIG-IP DNS

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  • Brant_Davis's avatar
    Brant_Davis
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    Oct 12, 2018

    When I use nslookup I am getting weird results. Currently it is resolving to all four GTMs but I get dns timeouts before the response. If I use dig it works everytime and is much faster with no timeouts.

     

    Has anyone else seen anything similar to this? This is my first time rolling out F5 DNS and just want to make sure everything is working properly.

     

  • Simon_Blakely's avatar
    Simon_Blakely
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    Oct 15, 2018

    Have you verified that all the devices are connecting via iquery?

     

    tmsh show gtm iquery

     

    Have you checked using dig to all the DNS servers?

     

    dig is the recommended tool for testing DNS, as nslookup does some unexpected things.

     

  • Brant_Davis's avatar
    Brant_Davis
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    Oct 15, 2018

    S Blakely,

     

    I have ran tmsh show gtm iquery and show all of them connected. Dig is returning proper results on all of the GTMs. Looks like nslookup was sending me down a rabbit hole with some mixed results.

     

    Thanks for the response and things to check.