Only applies to clustering columns, and is used to control the number of rows underneath each partition. If not specified, the default cluster distribution will default to FIXED(1).
For reference, let's take a look at a similar table that we built in Chapter 3, Effective CQL:
SELECT * FROM packt_ch3.security_logs_by_location_desc LIMIT 6;location_id | day | time_in | employee_id | mailstop-------------+----------+---------------------+-------------+---------- MPLS2 | 20180723 | 2018-07-23 14:04:59 | tejam | M266 MPLS2 | 20180723 | 2018-07-23 12:55:45 | tedk | M266 MPLS2 | 20180723 | ...