Understanding the U.S TLD System

By | April 7, 2014

.us is a country code TLD for U.S.A. Many sites over the internet will be using this TLD in many different ways. Understanding them can be simple if we get to know about the logic according to which domain names are arranged in an URL.

website monitoring serviceJon Postel was the original administrator of .us domain. He belonged to Information Services Institute (ISI) in University of Southern California (USC). Initially it was for premium use of United States Department of Defense. Only 3rd level or higher level domain registrations in geographical and organizational hierarchy was allowed. In April 2002, it was made open for 2nd level domain registrations. Currently the .us domain is administered by NeuStar Inc. under United States Department of Commerce.

Following are a few commonly used domains with .us domain

.com – commerce
.us – U.S.A
.org – organization
.co – company
.info – informative site
.net – network
.edu – educational site
.ac – academic institutions
.co.us – company in U.S.A
.res – research institute
.mil – military
.gov – governmentwebsite monitoring service

2nd Level domain name for states
A two letter 2nd level domain is given to each state in the United States based on ISO standards. For eg : .va.us refers to Virginia state in U.S. Similarly, .ny.us refers to New York in U.S. Some government owned bodies prefer using .gov domain.

Locality based domains
These are used in the format of “…us”
Eg : http://ci.boston.ma.us/

Locality name can include the name of a city, town or a village. Alternatively, they can also be used for county of government agencies. Other domains used are as follows.
dst: government agencies in administrative districts
cog: councils of government
k12: public elementary and/or secondary unified school districts
pvt.k12: private elementary or secondary schools
cc: community colleges
tec: technical and vocational schools
lib: public libraries
mus: museums
gen: general independent entities

.us Domain usage restrictions
The the United States government has imposed restrictions on the usage of .us domain. The restrictions are as follows:

  • Any United States citizen or resident,
  • Any United States entity, such as organizations or corporations,
  • Any foreign entity or organization with a bonafide presence in the United States

Spot checks are carried out by NeuStar Inc. to ensure that these restrictions are followed.