Load Balancing WIP across LTMs at 2 datacenters

It sounds like your DNS team is still handling DNS for the domain "company.com". We created a sub-domain "gtm.company.com" and had our normal DNS point to our GTM listeners for any DNS requests for the "gtm.company.com" domain. With that in place, we create entries like "app.company.com" in our normal DNS as a CNAME for "app.gtm.company.com". This gets the DNS request to our GTM and our GTM load balances appropriately ( Remember to set your DNS TTL to your needs ).

Correct when we add an address to the GTM such as app.company.com we have our DNS create a record and have been having them point these records to the VIP ip address but it sounds like we should be having them point it to the GTM listener. Am I heading down the correct path? Sorry in advance for the possibility of these questions be very open ended but I am just trying to get more into the use of the GTM and using it correctly and my DNS understanding is lacking a little. Thanks.

What we do is the following: We have our existing DNS refer any DNS requests for the gtm.company.com domain to the GTM Listener. If we want app1.company.com to be load balanced using the GTM we make a DNS entry in our main DNS tool called app1.company.com that is a CNAME for app1.gtm.company.com. A client resolving app1.company.com will get referred to app1.gtm.company.com which would then follow the DNS delegation and be requested from the GTM listener. The GTM will send a response with the IP of one of the LTM VIPs depending on the particular load balancing rules for that WideIP ( e.g. app1.gtm.company.com might return 10.10.10.11 or 10.20.10.11 which would be VIPs that can be on the same or different LTMs ). So the GTM itself has no VIP and all DNS queries that are to be load balanced by the GTM are referred to the GTM's listener. The GTM then responds with the IP address of an LTM VIP. If you have the GTM and the LTM modules ( they are separately licensed and provisioned ) running on the same physical Bigip it can be a bit confusing. Key parts of this. The GTM only works by answering DNS queries. It doesn't actually have VIPs. The GTM's listeners are where DNS queries should always be referred to. If you have your existing DNS infrastructure in front of the GTMs and it returns the IP addresses of VIPs for a DNS query, then you are not making use of the GTM. The existing DNS infrastructure must delegate the answer for GTM load balanced DNS queries to the GTM listener. I know I'm repeating myself, but I'm low on coffee. I hope this helps. Jason