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Wasfi_Bounni's avatar
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Aug 10, 2020

What is the default when the DNS/GTM pool is down

Hi;   When all members of a DNS pool associated with a wide IP for GSLB, are down. What DNS resource record is returned then? No record, NX Domain or what?     Kindly Wasfi
  • Simon_Blakely's avatar
    Aug 10, 2020

    The answer - like so many things - is it depends on the configuration of the GSLB pool and members, the DNS profile and the virtual server itself.


    K21520582: Overview of the DNS profile (11.x - 13.x)


    Both Pool members and pools have

    Alternate Loadbalancing

    Fallback Address

    as options, so they may provide resolution if the primary method fails.


    If GSLB resolution fails, then the DNS profile options kick in ...


    K21520582: Overview of the DNS profile (11.x - 13.x)


    Use BIND Server on BIG-IP

    allows the request to be passed to local bind - where results may be provided.

    This may just round-robin the Wide-IP addresses and return results to services that are down, so you may need to disable this option

    is there a DNS pool configured on the listener?

    the request may reach this point and be passed to another DNS server for resolution ...


    Unhandled Query Actions

    this controls how the DNS profile responds to a query that has not been resolved