reverse DNS


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reverse DNS

(Reverse Domain Name System) Name resolution that is the opposite of the standard forward DNS query. Most of the time, the DNS is queried with a domain name to return the host's IP address. With reverse DNS, also called "inverse DNS" and "reverse mapping," the DNS system is sent an IP address, and the domain name is returned.

Reverse DNS is used to log incoming traffic by domain name for statistical purposes. It is also used to prevent spam by determining if the email message is coming from the domain name indicated in the message header. Reverse DNS is an option and not mandatory in a DNS server. See DNS records, DNS and SPF.
References in periodicals archive ?
Another approach is Paul Vixie's Real-time Blackhole List (RBL)--an elegant combination of reverse DNS and MTA relay authentication that allows one to maintain a blacklist of spammers, sympathizers, and collaborators.
After analysis of a domain name's mail infrastructure, Email Security Grader performs diagnostics on MX records, reverse DNS, SPF, DNSBL, Open Relay and SMTP/POP3/IMAP authentication.
For the study, Return Path removed the data from servers that do not have reverse DNS and are clearly not supposed to be sending email.
SolarWinds Advanced Subnet Calculator now runs on Windows Vista and provides forward and reverse DNS resolution, response time, address translation and address class information.
DynDNS can also reject e-mail which comes from a server without proper reverse DNS.
Reverse DNS Lookup: allows administrators to look up a hostname using the IP address to find information about an IP address that is causing problems, to verify that a mail server has a reverse DNS entry, or to gather information about who is visiting your website.
Even a reverse DNS lookup report gives only one host name and misses the correct answer most of the time.