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 ?
DNS records work like a telephone book, converting human-readable website names like example.
The benefit of this approach is that owners of mail domains can independently register their own authorized IP addresses in DNS free of charge, and recipients of e-mail messages can perform queries of DNS records for SPF entries free of charge.
The idea is that organizations create their own key pair and publish the public key in their DNS records.
Ensure the provision of data lines and circuits, including services linked to them and to provide public IP addresses, DNS records management and on-line access to management and overview of the state.
Syrian Electronic Army attacked Qatar platform on October 19, 2013, and changed the DNS records of many government, private and military websites for about a day.
It appears that our account used to manage the DNS records registered at Network Solutions has received a fake password-reset request which was honored by the provider," the company wrote on its blog.
DNS Backup - Backup and restore DNS records from and to text files (no need for System State).
lt;p>Speculation is mounting that Baidu's web servers weren't actually hacked themselves, but instead its DNS records were compromised.
The aliased domain gets all the subdomains and DNS records of the original.
These systems call for email senders to publish the IP addresses of their outgoing mail servers in their DNS records.