PTR (Pointer) RR

Map an IP address to domain name
(not restricted to this purpose, though)

In case of IPv4
common and well-known upper level domain: in-addr.arpa.
four levels under the top level domain
1 label for 1 byte of the address
represent the address in the reverse order (the lowest byte appears first) 
    203.178.141.220 = www.kame.net.
    // dont' forget the trailing dot.
    220.141.178.203.in-addr.arpa. 1D IN PTR www.kame.net.