What is Reverse DNS?

出典: くみこみックス

Reverse DNS (Domain Name Method) lookup, also recognized by the acronym (rDNS), is the procedure by which somebody can appear up a host name given a specific IP address. Reverse DNS is also recognized 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. Generally, tools like a traceroute or a ping will do a reverse DNS lookup to decide the flow of site visitors from one particular point to an additional. One more common place for reverse DNS lookup is when accessing a persons e-mail. Many contemporary e mail providers will do reverse DNS lookups to figure out if an e-mail was sent from a identified spam address. Finally, reverse DNS can be utilised to make confident that there is a appropriate relationship in between the owner of a server and the owner of a domain name. This method, recognized as the guide to oil stock Forward Confirmed reverse DNS (FCrDNS) is utilised to put a stop to phishing internet sites and spammers.

What is IPv4 Reverse DNS lookup?

IPv4 Reverse DNS is a variety of reverse DNS that makes use of a reverse IN-ADDR entry with the particular domain in-addr.arpa. The IP wholesale baby baptism 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 individual was performing a reverse domain lookup for an address such as 192.168.1.1, he would do the lookup employing 1.1.168.192.in-addr.arpa.

What is IPv6 Reverse DNS lookup?

IPv6 Reverse DNS lookup is a variety of reverse DNS that makes use of the special domain ip6.arpa. As opposed to IPv4 Reverse DNS lookup, IPv6 Reverse DNS lookup does not use the regular IP address style of seeking up host names. Rather, it makes use of a sequence of nibbles, or four bit aggregations, in reverse order with every single number separated by a period. For instance, if a person was performing a reverse domain lookup for an address such as 2001:0db8:::::1428:57ab he would do the lookup employing b.a.7.5.8.2.four.1.....8.b.d..1...2.ip6.arpa.

What happens when there are several host de colores online names assigned to a single IP address?

A reverse DNS lookup will be in a position to determine all of the host names related with a particular IP address, although this practice is sometimes frowned upon. Many inexpensive internet hosting plans will offer you shared virtual hosts exactly where a lot of sites share space on the same IP address. Although this does not affect the validity of the details returned by a reverse DNS lookup, it can lead to troubles with other services.