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Reverse DNS (Domain Name Program) lookup, also identified by the acronym (rDNS), is the process by which someone can appear up a host name provided a certain IP address. Reverse DNS is also known in some areas as reverse resolving. It is the opposite of DNS lookup, by which somebody looks up an IP address provided a particular host name.
Why use Reverse DNS?
A reverse DNS lookup is usually performed for troubleshooting purposes. Frequently, tools like a traceroute or a ping will do a reverse DNS lookup to decide the flow of traffic from a single point to one more. Yet another frequent spot for reverse DNS lookup is when accessing a persons e mail. Numerous present day e-mail providers will do reverse DNS lookups to figure out if an e mail was sent from a known spam address. Finally, reverse DNS can be employed to make positive that there is a proper partnership in between the owner of a server and the owner of a domain name. This technique, identified as Forward Confirmed reverse DNS (FCrDNS) is employed to put a cease to phishing 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 particular 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 particular person was performing a reverse domain lookup for an address such as 192.168.1.1, he would do the lookup utilizing 1.1.168.192.in-addr.arpa.
What is IPv6 Reverse DNS lookup?
IPv6 Reverse DNS lookup is a kind of reverse DNS that uses the special domain ip6.arpa. Unlike IPv4 Reverse DNS lookup, IPv6 Reverse DNS lookup does not use the regular IP address style of seeking up host names. As an alternative, it uses a sequence of nibbles, or 4 bit aggregations, in reverse order with every single number separated by a period. For example, if a particular person was performing a reverse domain lookup for an address such as 2001:0db8:::::1428:57ab he would do the lookup utilizing b.a.7.5.8.2.4.1.....eight.b.d..1...two.ip6.arpa.
What occurs when there are numerous host names assigned to one particular IP address?
A reverse DNS lookup will be capable to figure out all of the host names related with a distinct IP address, although this practice is sometimes frowned upon. Numerous low cost internet hosting plans will provide shared virtual hosts where many web sites share space on the same IP address. Although this does not influence the validity of the details returned by a reverse DNS lookup, it can lead to issues with other services.
