With a variation on "If you have to ask how much, you can't afford it", let me ask what you mean by the "A and PTR records". I've been on Macs for quite awhile and never heard that terminology.
A and PTR records aren't Mac or PC things; they are Web and Internet domain name record things.
An "A record" is an IP address that goes with a particular domain name. The A record for finetunedmac.com is "74.53.32.254". When you type a domain name into, say, a Web browser, the browser goes toy our name server, asks for the A record for what you typed in, and then connects to that IP address.
The PTR is just the reverse. It is the "canonical name" associated with an IP address. Since many Web sites can live on one server, or many different services (like FTP or Web or SSH) can be associated with one IP address, the "canonical name" is the top level name associated with an IP address--the name of the server that multiple web sites are living on, for instance.
The A record for finetunedmac.com is "74.53.32.254;" the PTR for 74.53.32.254 is "root.gator255.hostgator.com". That tells you that finetunedmac.com is living on a server at IP address 74.53.32.254, and the full canonical name of the server it is living on is root.gator255.hostgator.com.