Question : DNS resolution across domains

My setup:  2 Active Directory domains running in the same building.  Both fully are trusted by each other.  Each AD domain has one DC, running AD-integrated DNS for its domain.  For *some* of the devices in one domain (not all), they can be pinged from a PC in the other domain without the domain suffix, while others cannot.  I can't figure out what the difference is.

E.g. on PC pc1.domain.local, I can ping pc11.domain2.local just by typing 'ping pc11' but if I try 'ping pc12' I get no response.  I do get a successful ping by using 'ping pc12.domain2.local'.  (Pinging the FQDN of any device always works.)

I have conditional forwarders set up on both DNS servers to point to the other.  All desktop PCs have both DNS servers set in their IPv4 settings. All device names/IPs are unique across both domains.  One server is Server 2003 x32 Std SP2.  The other is Server 2008 R2 Std.  Any help here is appreciated.

Answer : DNS resolution across domains

Your issue is not that DNS is being resolved cros domain for SOME names. It is NOT being resolved for ANY names. Windows is doing some local resolution where it can.

So in answer to your question.....

There is no difference. There is no DNS problen affecting SOME machines.

Use the Group policy i posted above to force ALL computers to lookup names in both xxxx.domain1.local and then xxxx.domain2.local formats.