Sub-Domain Delegation GTM/DNS


Lets say that you have hosted with a 3rd party DNS provider and you would like to create GTM (BigIP-DNS) DNS load balancing by utilizing Sub-Domain Delegation.

In this scenario, there are 2 GTM. One in each DC (DC-1 & DC-2). The basic set up has been completed and the GTMs are in a common sync-group.

Create A-Records for the 2 GTM using their Listener IP addresses: IN A IN A

gtm1 and gtm2 exist in DC-1 and DC-2 respectively and & are the listener IP address configured on gtm1 and gtm2.

Delegate the sub-domain to the GTM using NS Records: IN NS IN NS

Use CNAME records: IN CNAME

The above DNS records (A, NS & CNAME) will be added to the 3rd party DNS records that is hosting Any request for

will be sent to the 3rd party DNS provider which will then resolve to

because of the CNAME and that will be handled by the GTMs because of the NS & A records.

SOL277 – Sub-domain delegation.

9 thoughts on “Sub-Domain Delegation GTM/DNS”

  1. Hope you can help here. Need to create a sub domain in F5 GTM and delegate the zone to 3rd party NS.

    F5 is the SOA for the domain 3rd party wants to manage host records for the sub domain from their NS. Sub domain is

    Hope you can help point out the steps involved here. Thanks

  2. In the example that I provided, replace “domain” with “xyz” and replace “www” with “test”:

    A Records: IN A IN A

    NS Records: IN NS IN NS


    Create “” in the GTM.

  3. Does the subdomain have to be created as a master zone on the F5 that is the SOA for The subdomain would be “”

    In the A records section, shouldn’t the WIP be “test” instead?

    Because the F5 is doing the delegation should the NS records be pointing to the 3rd party NS instead that is cloud based? They are not using GTM

  4. In this particular case, GTM does not have any DNS files configured. GTM relies on an external DNS provider. All the DNS records exist in a non-GTM environment.

    For example, you can have the DNS records (A, NS, CNAME) at Rackspace or Amazon or any other DNS provider.

    Client makes a DNS query to “” which goes to the 3rd party DNS provider. The 3rd party DNS provider will utilize the A and NS record to provide the GTM information to the client. Client will query the GTM for “” and the GTM will respond with the IP of the VS that has the resources for “”. I will try to add a diagram to clarify the process in 1-2 days.

    In short, I think you are trying to configure DNS records on the GTM but my example is about delegating the DNS records to a 3rd party DNS provider.

  5. Hi mavenet. I’m not having success in following your steps. Hope you can provide some guidance.

    My goal is for the GTM to LB

    On DNS I have the following… IN NS IN A IN CNAME is the listener IP on the GTM is a A record WIP on the GTM

    nslookups and digs fail for

    To help my understanding, when a client requests, is it that the DNS tell the client to query for or the DNS does it on behalf of the client? I ask as my DNS is on a public network and GTM on private, but the client can route to both but the DNS cannot reach the private. Yes, I know, a weird lab setup!

  6. @Keith – LDNS makes the queries. Please, see if the diagram is of any help in clarifying. You should already have DNS configured for in a 3rd part DNS provider.

  7. Hi,

    If I have two domains hosted in Public dns that is and
    and looking for clients to access and via GTM

    In that case can we do following entries in DNS and if it will work ?


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