Setting up PTR for server IPs question

Hi Can someone explain to me I have cpanel whm Cloud VPS and 3 IPs connected to server i must set PTR for all this IPs ? example xxx.xxx.xxx.xx1 > hostname.mydomain xxx.xxx.xxx.xx2 > hostname..mydomain xxx.xxx.xxx.xx3 > hostname..mydomain on IPs xxx.xxx.xxx.xx1 i have ns1.mydomain xxx.xxx.xxx.xx2 i have ns2.mydomain