I can not believe it! One of the files come with 1and1 CentOS server installation is invalid. I do not know whether other types of servers from 1and1 have the same situation, but I am using 1and1 cloud server 64bit. The damaged file is /usr/share/zoneinfo/Europe/London. Every method I tried to set timezone to London (for now it is BST: British Summer Time), the system resets it to EDT: Eastern Daylight Time.
Normally I know how to set timezone on server, but cloud server is new to me. So when I see my methods do not work, my first reaction is looking for some secret method that works on cloud server. I have tried different ways to set timezone before I ever think about the London zoneinfo file is invalid. In a total hopelessness, I upload my PC’s /usr/share/zoneinfo/Europe/London from Fedora to CentOS, and it works.
Other zoneinfo files are OK as I observed.