dns packet size

[jeff donovan]

greetings,

i have been noticing my firewall denying udp packets that exceed 512.  
What is the correct packet size , and should I make any adjustments on  
ether the dns side or the firewall?

sample firewall log:
Oct  9 09:46:33 192.168.1.2 %PIX-4-410001: Dropped UDP DNS reply from  
outside:209.1.1.2/53 to inside:209.96.10.100/53661; packet length 523  
bytes exceeds configured limit of 512 bytes
Oct  9 09:46:33 192.168.1.2 %PIX-4-410001: Dropped UDP DNS reply from  
outside:209.1.1.2/53 to inside:209.96.10.100/53661; packet length 557  
bytes exceeds configured limit of 512 bytes
Oct  9 09:46:33 192.168.1.2 %PIX-4-410001: Dropped UDP DNS reply from  
outside:209.1.1.2/53 to inside:209.96.10.100/53661; packet length 523  
bytes exceeds configured limit of 512 bytes
Oct  9 09:46:33 192.168.1.2 %PIX-4-410001: Dropped UDP DNS reply from  
outside:209.1.1.2/53 to inside:209.96.10.100/53661; packet length 557  
bytes exceeds configured limit of 512 bytes
Oct  9 09:46:35 192.168.1.2 %PIX-4-410001: Dropped UDP DNS reply from  
outside:209.1.1.2/53 to inside:209.96.10.100/53661; packet length 519  
bytes exceeds configured limit of 512 bytes
Oct  9 09:46:38 192.168.1.2 %PIX-4-410001: Dropped UDP DNS reply from  
outside:209.1.1.2/53 to inside:209.96.10.100/53661; packet length 573  
bytes exceeds configured limit of 512 bytes

thanks for any insight

-jeff