F5 GTM response IP public

Hi guy

We have config GTM feauture on F5 i4800. We test nslookup abc.com.vn but we can not recevie IP public (123.123.123.123) for Pool member ( GSLB) ( Virtual server: 10.10.10.10 )

Please help me. I think that we need config irule .

Please

Thanks guy