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 look up a host name given a specific IP address. Reverse DNS is also identified in some places as reverse resolving. It is the opposite of DNS lookup, by which an individual looks up an IP address given a certain host name.

Why use Reverse DNS?

A reverse DNS lookup is normally performed for troubleshooting purposes. Frequently, tools like a traceroute or a ping will do a reverse DNS lookup to figure out the flow of traffic from one particular point to yet another. An additional widespread spot for reverse DNS lookup is when accessing a persons e-mail. Many modern e-mail providers will do reverse DNS lookups to decide if an e-mail was sent from a known spam address. Finally, reverse DNS can be utilized to make sure that there is a appropriate relationship amongst the owner of a server and the owner of a domain name. This method, known as Forward Confirmed reverse DNS (FCrDNS) is employed 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 uses a reverse IN-ADDR entry with the unique 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 individual 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. As opposed to IPv4 Reverse DNS lookup, IPv6 Reverse DNS lookup does not use the standard IP address style of looking up host names. Rather, it utilizes a sequence of nibbles, or four bit aggregations, in reverse order with each quantity 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 utilizing b.a.7.5.8.two.four.1.....8.b.d..1...two.ip6.arpa.

What occurs when there are numerous host names assigned to rent san diego criminal defense attorney a single IP address?

A reverse DNS lookup will be able to figure criminal defense attorney san diego on-line out all of the host names associated with a particular IP address, though this practice is at times frowned upon. A lot of low-cost net hosting plans will provide shared virtual hosts exactly where many websites share space on the exact same IP address. Despite the fact that this does not impact the validity reduced sentencing talk of the data returned by a reverse DNS lookup, it can lead to problems with other services.