Thanks, s.scherer.
But i know about GTM, i think i am failed to make all understand about my question. Lemme try again....
With Active-Passive mode ...We may be having only One VIP per application (common IP at both data center) . We may achieve the IP resolution without GTM/BIG-IP-DNS as well with traditional way i.e. "A" entry against a particular application VIP on LDNS or Public DNS that it's. Then Why do we require Listener entry (NS Entry or CNAME Entry on DNS) for GTM then... I mean what extra benefit i am getting here by using GTM with Active-PASSIVE.
Pls note again, that with ACTIVE-PASSIVE across two data center (One DC active and Other DC passive) i am referring in sense of stretched data center . i.e same IP Pools (Workload and VIP) will be shared among both the Data center.
However ....With ACTIVE-ACTIVE mode, we have different pools of Work Load or VIP per data center. hence per DC Listener IPs (same IPs for all applications) entry on require for NS Entry/ Delegation Record on Public DNS or LDNS pointing to application URL.
Rgds
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