Hello , The following steps are done by me in RHEL 4 machine 1. I have downloaded Only tzdata2007a.tar.gz from ftp://elsie.nci.nih.gov/pub/ 2. And I compiled using zic as Example: zic -d zoneinfo/ northamerica -L leapseconds -y yearistype.sh where zoneinfo is my temporary directory 3. And replaced the files to /usr/share/zoneinfo directory 4. Deleted Existing /etc/localtime 4. Copied the new zoneinfo Timezone as cp /usr/share/zoneinfo/America/Los_Angeles /etc/localtime 5. After the above execution I tested using zdump -v /etc/localtime | grep 2007 I found the result as Mar & Nov Correctly please tell me that 1. The above timezonedata .. i.e. tzdata2007a.tar.gz is enough for to update below listed OS List Of Linux ~~~~ ~~ ~~~~~ Redhat ES 4 Redhat ES 3 Enteprise Version ES 3. Enterprise Version WS 3 Enterprise Version 3 Linux 7.1 Redhat ES 4 update 3 Redhat ES 4 update 3 Redhat 7.1 2. Is Im required to download tzcode2007a.tar.gz and update with zic.c that is available in the tzcode2007a.tar.gz With Regards, Thiyagu