Reverse domain name notation

Reverse domain name notation (or reverse-DNS) is a naming convention for components, packages, types or file names used by a programming language, system or framework. Reverse-DNS strings are based on registered domain names, with the order of the components reversed for grouping purposes. For example, if a company making the product "MyProduct" has the domain name example.com, they could use the reverse-DNS string com.example.MyProduct as an identifier for that product. Reverse-DNS names are a simple way of eliminating namespace collisions, since any domain name is globally unique to its registered owner.

History

The first appearance of reversed DNS strings predated the Internet domain name standards. The UK Joint Academic Networking Team (

addresses were in use, mailers and gateway sites had ad-hoc workarounds to handle the differences, but could still be confused.

Reverse-DNS for identifier strings first became widely used with the

]

Examples

Examples of systems that use reverse-DNS notation are:

• Java platform
  for namespaces
• Apple's Uniform Type Identifier (UTI)^[1]
• The Android operating system, for classifying applications (because the Dalvik virtual machine was based on Java)
• backend used by GNOME
• The freedesktop.org Desktop Entry Specification^[2]
• iSCSI Qualified Naming

Some examples of reverse-DNS strings are:

• com.adobe.postscript-font,
  Adobe Systems's PostScript
  fonts
• com.apple.ostype,
  OSType
• org.omg.CORBA, Java library for CORBA
• org.w3c.dom, Java library for W3C's DOM
• org.kde.dolphin.desktop, a
  desktop
  file name

See also

• Non-Internet email address

References

External links

• Eclipse Naming Conventions
• Re: gnu.* namespace discussion