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Forum Discussion

aalkhuja_160331's avatar
aalkhuja_160331
Icon for Cirrus rankCirrus
Dec 25, 2017

iRule to change the DNS response IP inside the header

Hi there,   I want to create an iRule to change the address in the DNS Response header (coming from the DNS) from public IP to private. Knowing that F5 is not the DNS itself (it is before the DNS)...
application delivery
iRules
LTM
Stanislas_Piro2's avatar
Stanislas_Piro2
Icon for Cumulonimbus rankCumulonimbus
Dec 25, 2017

you can try something like this:

when DNS_RESPONSE {
    set rrs [DNS::answer]
    DNS::answer clear    
    foreach rr $rrs {
        if {[lindex $rr 4] equals "4.3.2.1"} {
                DNS::answer insert "[lindex $rr 0] [lindex $rr 1] [lindex $rr 2] [lindex $rr 3] 1.2.3.4"
        } else {
            DNS::answer insert $rr
        }
    }

}