DNS records


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DNS records

A DNS server contains a "zone file" for each domain, and the zone file is made up of "resource records" (RRs). The most common are described below. See DNS.

Forward DNS and Reverse DNS (A and PTR)
The Address (A) record associates a domain name or subdomain with an IP address, which is the primary purpose of the DNS system. The @ sign identifies "this domain;" for example, A @ nnn.nnn.nnn.nnn means this is the IP of this domain.

The Pointer (PTR) record provides data for reverse DNS, which is used for logging the domain name and verification purposes. Also called "inverse DNS," the PTR record is an option. See reverse DNS.

Aliasing Names (CNAME)
The Canonical Name (CNAME) record is an alias that points to other names. It is commonly used to map subdomains to the domain without having to enter the IP address again. For example, CNAME mail @ associates the mail subdomain to the this domain.

DNS Name Servers (NS)
Two Name Server (NS) records identify the authoritative DNS servers for the domain. Required for redundancy, the secondary name server queries the primary server for changes.

Mail Servers (MX)
The Mail Exchange (MX) record identifies the server to which email is directed. It also contains a priority field so that mail can be directed to multiple servers in a prescribed order.

Text Record (TXT)
A TXT record can be used for any documentation or identification purpose. It is also used to provide information to the SPF email authentication system. See SPF.

Start of Authority (SOA)
The Start of Authority (SOA) record contains the name of the primary DNS server, which must correspond to an NS record in the file.
COMMON RECORD TYPES SUMMARYA (forward DNS - IPv4)
  associate subdomain to 32-bit IP

 PTR (reverse DNS)
  associate IP address to a subdomain

 CNAME (aliases)
  associate an alias to a domain

 SOA (name of primary nameserver)

 NS (name server)
  associate a domain to a DNS server

 TXT (documentation)

 DNAME (aliases)
  associate an alias to a subdomain

 MX (mail server)
  associate mail to a mail server

 AAAA (forward DNS - IPv6)
  (1st IPv6 record)
  associate subdomain to 128-bit IP

 A6 (forward DNS - IPv6)
  (future IPv6 record)
  associate subdomain to 128-bit IP
References in periodicals archive ?
(http://grahamcluley.com/2013/10/metasploit-website-hijacked-pro-palestinian-hackers/) According to security expert Graham Cluley , DNS records "work like a telephone book, converting human-readable website names like metasploit.com into a sequence of numbers understandable by the internet.
Instead, they are putting the blame on their DNS records.
In mid-2009, D-Link integrated Completely Automated Public Turing test to tell Computers and Humans Apart (CAPTCHA) into its popular home and small office routers to thwart worms designed to access a router and alter the victim's DNS records to divert traffic toward the attacker's network.
to tell Computers and Humans Apart (CAPTCHA) into its home and small office routers to stop worms designed to access a router and alter the victim's DNS records to divert traffic toward the attacker's network.
"It looks like their domain account credentials may have been snagged," said Paul Ferguson, a researcher with the antivirus vendor Trend Micro.<p>That's the same technique that was used to hijack Twitter, when Iranian Cyber Army hackers were apparently able to log in to the account used to manage Twitter's DNS records and redirect visitors to another Web server that posted a message similar to the one spotted on Baidu.com.
These Trojan horses then attack the router and alter their DNS records to divert all traffic through a target network.
Their software provisions over 30 million IP address and DNS records for customers in North and South America, Europe, and Asia-Pacific.
The new Proactive Security Monitor delivers updates on additional security information and users are able to monitor the effectiveness of their corporate firewall and constantly check their DNS records through a web-based interface.