Error text when executing zabbix_agentd.exe "The procedure entry point DnsFree could not be located in the dynamic link library DNSAPI.dll." on Windows 2000. WinDNS.h (starting at line 1629 in Windows SDK v6.0a) overrides the DnsRecordListFree function to DnsFree for _WIN32_WINT>= 0x0501 (Windows XP). This is a problem because DnsFree was added to Dnsapi.lib in Windows XP so is therefore unavailable in Windows 2000.
Probable solution is adding "_WIN32_WINNT=0x0500" or similar symbol for Windows SDK headers to process.
I added this directly to the net.c compilation command in build\win32\project\Makefile_agent because adding to the CFLAGS macro caused error with system.c compilation. I leave it to much more capable programmers to determine the optimal course of solution.
Forum discussion: http://www.zabbix.com/forum/showthread.php?t=26369
Using the Windows Headers http://msdn.microsoft.com/en-us/library/aa383745(v=vs.85).aspx