Starbase 28
Starbase 28 was a Federation starbase administered by Starfleet. The base consisted of a space station, capable of docking multiple starships. The starbase's control center was referred to as Ops. 

In the 2250s, Cadet Thira Sidhu was posted to Starbase 28 while her application to the  was being considered. (She was told it had been rejected, but this subterfuge was part of her evaluation.) Sidhu was working in Inventory Two when the starbase appeared to have come under attack. 

During the attack, a voice on the intercom claimed that the station had sustained breaches on levels 4, 5, 7, and 9. The damage on level 4 prevented access to the brig from locations near Inventory Two.

Security officers brought Captain Christopher Pike,  handcuffed and masked, to Inventory Two and told Cadet Sidhu that Pike had mutinied and that she was to keep him prisoner. Pike told her that the station was under attack by Tholians and ordered her to release him; Cadet Sidhu refused. 

The attack was, in fact, a simulation, designed by Lieutenant Commander Una to test Cadet Sidhu's suitability to serve on the Enterprise. She passed the test, and was assigned to the Enterprises engineering department. ()

Personnel

Appendices

Background information
The Station 28 Computer voice was provided by Colette Whitaker.

In foreign-language Netflix broadcasts of  (including in Klingonese), the starbase seen in that episode is captioned as the foreign-language equivalent of "Starbase 28". However, there is no corresponding caption in the English-language versions. Despite this, the subtitles from the DIS Season 1 Blu-ray also label the facility as "Starbase 28", and the same starbase's configuration matches the graphic from "Ask Not".

External link 
 
0028, Starbase