I recently worked through an issue with a client trying to detect data drift across some servers that were located in different timezones. Unfortunately, several of the tables had timestamp fields and were set to a default value of CURRENT_TIMESTAMP. From the manual, here is how MySQL handles timezone locality with timestamp fields:
TIMESTAMP columns are converted from the current time zone to UTC for storage, and from UTC to the current time zone for retrieval.
This can result in every row being deemed out of sync when each server is using in it’s own timezone. Fortunately, there is a workaround for this as a result of how pt-table-checksum/pt-table-sync calculate their checksums. Lets look at an example: