Need to configure GTM ....

Good evening. I'll try to answer your questions,

 

In regards to GTM Listener break-down, have a look at: https://support.f5.com/kb/en-us/products/big-ip_gtm/manuals/product/gtm_config_guide_10_1/gtm_listeners.html1010790. The guide is for v10, but its still very relevant for BigIP v11.

 

To summarize the guide, with GTM Listeners you can create exceptional configurations. They are not mandatory.

 

This is what you may consider a default GTM/DNS setup:

 

1. Your ISP DNS (handles all external IP ranges and public domains that do not belong to you)

 

2. F5 GTM DNS (handles all external IP ranges and external domains that belong to you. Just configure Wide IPs, no need for GTM Listeners, unless you have exceptional requirements)

 

3. Internal Network DNS (handles all internal IP ranges and domains)

 

 

For reference, here's some stuff you can do with GTM Listeners:

 

As an exception to 1,

 

you can configure a GTM Listener to intercept an outgoing request to 8.8.8.8 (belongs to Google), and say it resolves to 'hahaha.ihackedgoogle.com' instead.

 

As an exception to 2,

 

you can configure a GTM Listener to bypass GTM DNS resolution for an external IP 1.1.1.1 (lets say it belongs to You), and have it routed to your Internal Network DNS server for an answer.

 

As another exception to 3,

 

you can configure a GTM Listener using an internal IP, i.e. 192.168.1.1, and have your GTM provide an answer instead of your Internal Network DNS server, as would happen otherwise.