Hi:
Recently, I wanted to write a program to watch the change of timezone database. I got newest version from this address: https://data.iana.org/time-zones/releases/tzdata2021a.tar.gz. I used zic (version: zic (tzcode) 2020c, system: CentOS Linux release 7.6.1810 (Core)) to generate the zoneinfo.  I pick up some zones with local timeto calculate utc time to verify the changes using both the new and currently used version tzdata, here is diff:

zone local time by 2021a  utc time by 2020d utc time
America/Adak 2022-11-01 00:00:00 2022-11-01 09:00:00 2022-11-01 10:00:00
America/Anchorage 2022-11-01 00:00:00 2022-11-01 08:00:00 2022-11-01 09:00:00
America/Asuncion 2022-10-01 00:00:00 2022-10-01 04:00:00 2022-10-01 03:00:00
America/Atka 2022-11-01 00:00:00 2022-11-01 09:00:00 2022-11-01 10:00:00

Those zones are not changed from version 2020d to 2021a. I am very confused and not sure if I generated the zoneinfo in the right way. Here was what do:

# mkdir zoneinfo
# cd tzdata2021a
# zic -d ../zoneinfo -L  ./leapseconds africa antarctica asia australasia europe northamerica southamerica etcetera backward factory

I was wondering if you could provide me some help. I really appreciate your reply. 

Sincerely,
wangmm