I import my requester from Domain Controller for example name as"C"

In Admin --> Requester --> Edit --> Department Details:

I set For example:  Site = "A" and Department Name = "B"

And in --> Log in Details:  Domain = "C"

Also I associated the technician to site "A" and the technician's Domain  is "C"

I want to know how request from this requester can automatically detect it's technician and send hisher requests to the associated technician.