Original Publication Date: 02/15/2006
Updated Date: 09/08/2016
You should consider using this procedure under the following condition:
When you use a BIG-IP DNS or BIG-IP Link Controller system to provide wide area load balancing services, you may need to delegate authority for specific host names from the primary DNS server to the BIG-IP system.
You must meet the following prerequisites to use this procedure:
Primary DNS subdomain delegation
Complete the following steps to configure the DNS server to delegate a subdomain to the BIG-IP DNS or BIG-IP Link Controller system.
Impact of procedure: Due to the nature of DNS, F5 recommends that you perform this procedure during a maintenance window with sufficient time allotted for DNS propagation.
Make sure the subdomain contains the host names to be load balanced. In most cases, it makes sense to create a new subdomain that is used only for this purpose. For example, the subdomain name wip is often used.
On the primary DNS server, delegate authority for the subdomain to the BIG-IP DNS or BIG-IP Link Controller system by modifying the parent zone to include nameserver (NS) records for the new zone, and address (A) records for the new nameservers referenced in the NS records.
For example, to delegate authority for the wip.domain.com subdomain to the BIG-IP DNS systems named gtm1.domain.com and gtm2.domain.com, the parent zone file should contain the following entries:
wip IN NS gtm1.domain.com. IN NS gtm2.domain.com.
gtm1.domain.com. IN A 192.168.101.254
gtm2.domain.com. IN A 192.168.102.254
For example, to have the BIG-IP DNS or BIG-IP Link Controller system load balance traffic for the www.domain.com host name, the domain.com zone should contain the following entry:
www.domain.com. IN CNAME www.wip.domain.com
When a client requests DNS resolution for the host name www.domain.com, the DNS server that is authoritative for the domain.com domain responds with the CNAME (alias) record www.wip.domain.com. The client then requests resolution for the host name www.wip.domain.com. Since the domain.com zone points to gtm1.domain.com and gtm2.domain.com as the authoritative nameservers for the subdomain wip.domain.com, the resolution request for www.wip.domain.com is then sent to one of the BIG-IP DNS systems. The BIG-IP DNS system sends a response to the request with the most appropriate A (address) record based on the wide IP configuration.