Forum Discussion
Stevenson_88156
Nimbostratus
NimbostratusGTM DNS Question
Hi
I hope this is the correct forum to post this question. Our company just recently bought new F5 devices and I have a questions specifically with GTM. In all the documentation I found about GTM, I came across this only document that most clearly explains how DNS delegation works with F5 GTM.
https://support.f5.com/kb/en-us/sol...ol277.html
From my understanding, you will need to create an A record for the GTM listener (which is also the self IP), an NS record that delegate the Wide IP host domain name to the GTM listener and then a CName that points the actual web site Host to the Wide IP host domain name.
However, without understanding the inner workings of DNS, I was wondering if I could instead create the NS record with the actual web site host name to delegate to the GTM Listener and create the host name as wide IP thereby skipping the creation of the CName. An example of this is as follows:
1. Create NS Record (name.domain.com -> gtm1.domain.com)
2. Create a wide IP name "www.name.domain.com".
In addition, if in the future if we decided to create deeper sub domain layers (ie. test.name.domain.com), is it possible for us to just create new wide IP address of that name without making more changes to the Primary DNS.
Thanks.
- Chris_Miller
Altostratus
You shouldn't have to CNAME anything. I've used Link Controller quite a bit and that's pretty similar to GTM. I'd simply do a setup like this:
1. Floating listener IP on GTM of 1.1.1.1 (obviously replace this ip)
2. A-record in your DNS zone (let's assume example.com) in this case "gtm-listener IN A 1.1.1.1" (obviously use your own name/ip combo)
3. NS record for "www.example.com" would be "www IN NS gtm-listener"
4. Wide-IP configured on GTM to map www.example.com to whatever VSes you need.
Make sense? 
Stevenson_88156Thank you very much. That really helps my understanding. Now I have another question. If we needed to load balance the URL "www.name.example.com" in our current DNS zone (example.com), would the following be correct: 1. NS record for "name.example.com" would be "name IN NS gtm-listener" 2. Create a wide IP called "name.example.com". In addition add the alias "www.name.example.com". Would this work? Thanks.- Chris_MillerPosted By Stevenson on 07/26/2010 02:18 PM
Thank you very much. That really helps my understanding. Now I have another question. If we needed to load balance the URL "www.name.example.com" in our current DNS zone (example.com), would the following be correct: 1. NS record for "name.example.com" would be "name IN NS gtm-listener" 2. Create a wide IP called "name.example.com". In addition add the alias "www.name.example.com". Would this work? Thanks.
I'm afraid I haven't done GTM enough to answer this one, but why not just do "www.name IN NS gtm-listener" in DNS and "www.name.example.com" in GTM? I'm just not clear on how GTM uses CNAMEs.
