A company needs to use a custom value when making persistence decisions. Which F5 product provides this functionality?

iControl is F5's REST and SOAP management API used for configuration automation - it operates at the management plane and does not process live traffic or influence per-connection persistence.

iRules exposes the 'persist' command and full access to traffic payload, headers, and custom variables at runtime, giving administrators complete flexibility to hash or match on any extracted value - such as a proprietary header or payload field - when directing a client to a specific pool member. No built-in persistence profile supports arbitrary custom keys, making iRules the only BIG-IP mechanism for this requirement.

iApps are declarative application deployment templates that simplify service provisioning - they do not execute during live traffic forwarding or provide custom runtime persistence logic.

iHealth is a cloud-based diagnostic analysis service for qkview files - it plays no role in data plane traffic forwarding or persistence decisions.