NimbostratusIf your intent is to have one or more FQDN you specify in a datagroup automatically resolve to their respective IP addresses, then I am afraid that is not possible. First of all, an IP address type datagroup must contain an IP address or IP address range as the key portion of the "key := value" pair. (The "value" portion is optional.) It cannot contain text such as an FQDN. (A string type datagroup could be used for a list of FQDN, but they will not be automatically resolved.) However, you can use an IP address type datagroup and dynamically update its contents using an external source, such as a TMSH script or iControl program that runs periodically. An iRule can only read a datagroup; it cannot modify the contents. (Read more about datagroups here.)
You might look at the RESOLV::lookup command which provides a way to dynamically obtain the IP address(es) of an FQDN at run-time. However, I would use extreme caution with this approach, as the iRule will repeat the lookup for each connection, and that can quickly consume resources and impact performance, especially if you need to resolve more than one FQDN or if traffic volumes are high.
