Time in Kazakhstan
Even though its territory spans four geographical time zones (from +3 to +6), standard time in Kazakhstan is either UTC+05:00 or UTC+06:00. These times apply throughout the year as Kazakhstan does not observe Daylight saving time. IANA time zone database 
The tz database identifies seven zones for Kazakhstan. Data in columns marked * are from the file zone.tab of the database. According to an email on the tz mailing list, Kostanay Region could be part of Asia/Qyzylorda . Time by region 

Notes:
 (1) Almaty, Astana and Shymkent cities have the status of State importance and do not relate to any region. (2) Baikonur city has a special status because it is currently being leased to Russia with Baikonur cosmodrome until 2050. Time unification proposal 
The Ministry of Ecology of Kazakhstan say that Kazakhstan may unify the UTC offset to UTC+6, i.e. the Astana time. It was assumed that the proposal could be implemented on the night of November 30 to December 1. See also 
 Omsk Time

References