Ping domain name and get reply from BDC’s IP address

I have 2 DCs(DC1,DC2) both of them running Windows server 2003 R2 standard and domian funtional level is windows server 2003.
DC1 is PDC, DC2 is secondary BDC.
From clients i ping the domain name(ext: Ping contoso.com),sometine i get reply from IP address of DC2, sometime from DC1. But now BDC is missing Sysvol and Netlogon share so group policies could not be applied.
operations master is still DC1.
I want to get repy from DC1 when ping the domain name and group policies can be applied.
anyone can tell me how to fix this?