Just a code snippet on how to spoof a DNS query using Python and Scapy. You can replace the source address with anything you want.
from scapy.all import *
import sys
if len(sys.argv)>1:
print sys.argv[1]
# a normal lookup
#spoofed_pkt = (IP(src="173.194.112.88",dst="8.8.8.8")/UDP(dport=53)/DNS(qd=DNSQR(qname="torproject.org"))
# a reverse lookup
spoofed_pkt = (IP(src="173.194.112.88",dst="8.8.8.8")/UDP(dport=53)/DNS(rd=1,qd=DNSQR(qname=sys.argv[1]+".in-addr.arpa", qtype='PTR')))
send(spoofed_pkt)