How to create Daylight Savings time Start and End function in SQL Server With Incident table

I need to create a function in SQL server that returns daylight savings time start datetime and daylight savings time end datetime for CST.

Below is the query.. Please help me in getting Day light savings for CST .. I need CST for Day light savings for Opened and Closed.

SELECT
    sc_task_full.number
    , sc_task_full.dv_priority
    , sc_task_full.dv_assignment_group
    , sc_task_full.dv_assigned_to
    , sc_task_full.dv_cmdb_ci
    , sc_task_full.opened_at
    , sc_task_full.closed_at
FROM
    sc_task_full