The document discusses DNS (Domain Name System) records. It explains that DNS is a hierarchical naming system that maps hostnames to IP addresses. DNS records are the basic data elements that allow DNS servers to perform this mapping. The document describes several important DNS record types including A records, which map hostnames to IPv4 addresses; AAAA records, which map to IPv6 addresses; CNAME records, which map aliases to hostnames; and MX records, which specify mail servers for a domain. It also briefly mentions SOA, PTR, and SRV records along with sources for further information on DNS records.

1. DNS Record
Ting Kang
COM585, Fall 2011
University of Washington

2. What is DNS ?

3. Root
com. org. edu. net.
The DNS (Domain Name System) is a distributed
hierarchical naming system for computers, services, or any
resources connected to the Internet or a private network. It’s
used to resolve the hostname to IP address.

4. DNS Record (Resource Record) is the basic data element
in DNS. It allows the DNS server to convert name request
into IP addresses that specifies where on the Internet the
server is located. In these domain servers, different record
types are used for different purposes.
SOA
A
What is DNS Record ?

5. • An A (Address) record maps a hostname to an IP address.
The AAAA Record, is very similar to an A record. It is
also associate a domain name with the IP address.
However, these records are used to specify an IPv6, while
A records are used to specify an IPv4.
Hostname Type Data
domain.com A 123.456.789.10
www.domain.com A 123.456.789.10
A Record / AAAA Record

6. • A CNAME (Canonical NAME) record maps an alias
name to another hostname which is in turn mapped to an
IP address by an A record.
Hostname Type Data
domain.com A 123.456.789.10
www.domain.com CNAME domain.com
CNAME Record

7. • An MX (Mail exchanger) record specifies the hostname
that will process incoming email for a domain.
MX Record Priority
1mail.domain.com 1
2mail.domain.com 2
MX Record

8. • SOA Record (Start of Authority)
 The DNS server that has the most authority.
 It includes the primary name server, the email administrator of
the domain, the domain serial number.
• PTR Record (Pointer)
 A PTR record maps an IP address to a hostname.
• SRV Record (Service)
 SRV records relate to a particular service of the domain, like
FTP or SIP, rather than a specific machine the way A or C-
name records do.
More DNS record types

9. • http://en.wikipedia.org/wiki/Domain_Name_System#DN
S_resource_records
• https://www.the.net/tools/docs/dns.php
• http://help.register.com/app/answers/detail/a_id/487/~/wh
at-is-a-dns-record-and-how-long-will-it-take-before-my-
dns-record-changes
• http://www.youtube.com/watch?v=cwT82ibOM2Q
• http://www.youtube.com/watch?v=tD6B-
nOCOCY&feature=related
Sources