It is a contrast to forward DNS and set up by configuring pointer record in a particular DNS server. The forward DNS uses address records. While registering a domain name with a domain registrar one does have the responsibility for the forward DNS domain. The company that allows you to make your IP addresses will let you know how to change your reverse DNS PTR records. As a substitute to this option, a range of IP addresses may be delegated to you by the company in which reverse DNS and PTR records will have to be configured by you to your DNS server.

Now the question arises that whether the reverse DNS is necessary or not?

At times some inexperience administrator configures the forward DNS and become less careful about configuring the reverse DNS which to some extent work nicely. Internet browsing is at a terrific speed but this will not be all that a good option because the rest might become workless. Internet protocol and some extensions of other internet protocol need the reverse DNS. So without acquiring Reverse DNS may cause many problems. Some most enterprise management systems, SMTP servers, IRC, and much network backup system can be badly affected by reverse DNS undone. So the correct configuration of the reverse DNS on the right time needs to be ensured right from the way it goes.

Going back in the history suggests that the allocation of the IP addresses was made in the blocks of 256 each falling upon an octet boundary. The delimitation of each block by the dot separators made the configuration of the IP record lot more comfortable. Nowadays the ancient way of names server’s configuring to perform the reverse DNS will not work. This problem was handled by the division of RFC 2317 that used CNAMES to correspond to each block. Despite being legally acceptable to have different PTR records, most of the DNS entries have yet one PTR record and rightly so. Having too many PTR records on one IP address without any need is not appropriate too.

Having too many PTR records can cause some problems. At first that makes the DNS packet to be too large and then of course the programs that always expect only one PTR record to come. Some other records of fewer standards such as TXT record and the LOC record can also be kept in the DNS tree.