domain_prefix

This is a library to determine the registration prefix for a given domain and can be used to assert if a given domain name is valid or not.

The registered_domain method returns the name of the registered domain associated witha given hostname, or Fully Qualified Domain Name (FQDN):

DomainPrefix.registered_domain('test.example.com')
# => 'example.com'
DomainPrefix.registered_domain('test.example.ca')
# => 'example.ca'
DomainPrefix.registered_domain('test.example.co.uk')
# => 'example.co.uk'

The public_suffix method returns the suffix into which this domain is registered:

DomainPrefix.public_suffix('test.example.com')
# => 'com'
DomainPrefix.public_suffix('test.example.ca')
# => 'ca'
DomainPrefix.public_suffix('test.example.co.uk')
# => 'co.uk'

Note that the "public suffix" component of a domain can be quite lengthy depending on the context. Some countries have three or more levels of structure in their TLD.

In some cases there are quasi-TLD listings in this file relating to common hosting platforms like xs4all.space or dynamic DNS providers like DynDNS with suffixes like dnsalias.com.

As no distinction is made in the source .dat file between these hosting companies and TLD registry structures it's not possible to differentiate in this library either.

To update the data used to make the domain determinations, there's a rake task:

rake domain_prefix:update

The test case data is pulled from a separate source:

http://mxr.mozilla.org/mozilla-central/source/netwerk/test/unit/data/test_psl.txt?raw=1

The source of this data is the Public Suffix List which is licensed under the Mozilla Public License 2.0. A portion of this project is included in this gem.

Copyright (c) 2009-2019 Scott Tadman, PostageApp Ltd. See LICENSE for details.