DNSはUDPなんで、具体的には、

# netstat -s -p udp
udp:
1996 datagrams received
0 with incomplete header
0 with bad data length field
0 with bad checksum
0 with no checksum
0 dropped due to no socket
0 broadcast/multicast datagrams dropped due to no socket
0 dropped due to full socket buffers
0 not for hashed pcb
1996 delivered
1996 datagrams output

の、droppedなんちゃらのところがカウントアップされるようだと、
いまいちですね