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Forum Discussion

KingMeow_3883's avatar
KingMeow_3883
Icon for Altostratus rankAltostratus
Mar 26, 2015

GTM iRule to forward dns request to a pool of DNS servers

Hi,   On the GTM, is it possible to use an iRule to disable wideIP and forward a dns request to a pool of DNS servers instead?   I have a situation where LTM pool members attempt to resolve eac...
StephanManthey's avatar
StephanManthey
Icon for Nacreous rankNacreous
Mar 28, 2015

Hi KingMeow,

assuming your pool of nameservers associated with your listener is already used to handle incoming queries which cannot be resolved by GTM, right?

An iRule will now disable local GTM processing if a client request is received from a local network: 
when DNS_REQUEST {
    if {[IP::addr [IP::client_addr] equals 10.131.131.0/24]} {
        log local0. "dns query from local network: <[IP::client_addr]>"
        DNS::disable gtm
    }
}

Make sure to create this iRule as an LTM iRule and associate it with the lister (actually a virtual server in the LTM context as well).

So your assumption is right as I just verified in my lab.

Instead of verifying versus a single network you may want to use the class command in combination with a datagroup to exclude multiple client networks.

Thanks, Stephan