DNS PTR Records subnet

[Sangoi, Nehal (GE Supply, consultant)]

Hi
 
How can I define my reverse record zone files for the subnet like
"3.160.232.0/22"
 
should it be "160.3.in-addr.arpa"
 
or should it be like 
"235.160.3.in-addr.arpa"
"234.160.3.in-addr.arpa"
"232.160.3.in-addr.arpa"
 
 
Please suggest.
 
 
Thanks
Nehal