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Reverse DNS (Domain Name System) lookup, also identified by the acronym (rDNS), is the procedure by which someone can appear up a host name given a distinct IP address. Reverse DNS is also known in some areas as reverse resolving. It is the opposite of DNS lookup, by which someone looks up an IP address given a certain host name. Why use Reverse DNS? A reverse DNS lookup is generally performed for troubleshooting purposes. Typically, tools like a traceroute or a ping will do a reverse DNS lookup to decide the flow of targeted traffic from one point to another. One more common location for reverse DNS lookup is when accessing a persons e-mail. A lot of modern e mail providers will do reverse DNS lookups to establish if an e-mail was sent from a identified spam address. Ultimately, reverse DNS can be utilized to make sure that there is a suitable relationship amongst the owner of a server and the owner of a domain name. This technique, recognized as Forward Confirmed reverse DNS (FCrDNS) is utilized to put a quit to phishing web sites and spammers. What is IPv4 Reverse DNS lookup? IPv4 Reverse DNS is a variety of reverse DNS that utilizes a reverse IN-ADDR entry with the special domain in-addr.arpa. The IP address represented in the in-addr.arpa domain is written in reverse order to the usual way that the IP address is written. For example, if a person was performing a reverse domain lookup for an address such as 192.168.1.1, he would do the lookup making use of 1.1.168.192.in-addr.arpa. What is IPv6 Reverse DNS lookup? IPv6 Reverse DNS lookup is a variety of reverse DNS that utilizes the particular domain ip6.arpa. Unlike IPv4 Reverse DNS lookup, IPv6 Reverse DNS lookup does not use the standard IP address style of looking up host names. Rather, it makes use of a sequence of nibbles, or four bit aggregations, in reverse order with each number separated by a period. For example, if a individual was performing a reverse domain lookup for an address such as 2001:0db8:::::1428:57ab he would do the lookup employing b.a.7.5.8.two.four.1.....8.b.d..1...2.ip6.arpa. What takes place when there are many host names assigned to 1 IP address? A reverse DNS lookup will be in a position to figure out all of the host names associated with a specific IP address, even though this practice is often frowned upon. Several low cost net hosting plans will provide shared virtual hosts where a lot of websites share space on the same IP address. Even though this does not have an effect on the validity of the data returned by a reverse DNS lookup, it can lead to difficulties with other services. arraignment hearing