What is Reverse DNS?

Reverse DNS (Domain Name System) lookup, also recognized by the acronym (rDNS), is the approach by which somebody can look up a host name given a particular IP address. Reverse DNS is also identified in some locations as reverse resolving. It is the opposite of DNS lookup, by which an individual looks up an IP address given a distinct host name.

Why use Reverse DNS?

A reverse DNS lookup is normally performed for troubleshooting purposes. Generally, tools like a traceroute or a ping will do a reverse DNS lookup to decide the flow of visitors from a single point to an additional. One more typical location for reverse DNS lookup is when accessing a persons email. A lot of contemporary email providers will do reverse DNS lookups to decide if an email was sent from a identified spam address. Finally, reverse DNS can be employed to make positive that there is a correct relationship in between the owner of a server and the owner of a domain name. This technique, known as Forward Confirmed reverse DNS (FCrDNS) is utilized to place a quit to phishing web sites and spammers.

What is IPv4 Reverse DNS lookup?

IPv4 Reverse DNS is a sort 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 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 makes use of the unique domain ip6.arpa. Unlike IPv4 Reverse DNS lookup, IPv6 Reverse DNS lookup does not use the normal IP address style of hunting 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 instance, if a person was performing a reverse domain lookup for an address advent wreath such as 2001:0db8:::::1428:57ab he would do the lookup making use of b.a.7.5.8.2.4.1.....8.b.d..1...two.ip6.arpa.

What happens when there are multiple host names assigned to 1 IP address?

A reverse DNS lookup will be able to establish all of the host names associated roman chasuble with a particular IP address, although this practice is sometimes frowned upon. Numerous low cost web hosting plans will supply shared virtual hosts where several websites share space on the exact same IP address. Even firefighter cross though this does not have an effect on the validity of the information returned by a reverse DNS lookup, it can lead to troubles with other services.