dig on RHEL6 has a different behavior than in RHEL5, related to the @server syntax:
root@rhel6# dig @some.dnsserver.com any some.example.com dig: couldn't get address for 'some.dnsserver.com': not found
It seems it doesn't try to revolve the parameter for the specified dns server. Any idea why is that? Is it to avoid making another dns request?