________________________________________________________________________________ Network Working Group A. Cooper Request for Comments: 1480 J. Postel Obsoletes: 1386 June 1993 The US Domain Status of this Memo This memo provides information for the Internet community. It does not specify an Internet standard. Distribution of this memo is unlimited. [...] 1. INTRODUCTION 1.1 The Internet Domain Name System The Domain Name System (DNS) provides for the translation between hostnames and addresses. Within the Internet, this means translating from a name such as "venera.isi.edu", to an IP address such as "128.9.0.32". The DNS is a set of protocols and databases. The protocols define the syntax and semantics for a query language to ask questions about information located by DNS-style names. The databases are distributed and replicated. There is no dependence on a single central server, and each part of the database is provided in at least two servers. The assignment of the 32-bit IP addresses is a separate activity. IP addresses are delegated by the central Internet Registry to regional authorities (such as the RIPE NCC for Europe) and the network providers. To have a network number assigned please contact your network service provider or regional registration authority. To determine who this is (or as a last resort), you can contact the central Internet Registry at Hostmaster@INTERNIC.NET. In addition to translating names to addresses for hosts that are on the Internet, the DNS provides for registering DNS-style names for other hosts reachable (via electronic mail) through gateways or mail relays. The records for such name registrations point to an Internet host (one with an IP address) that acts as a mail forwarder for the registered host. For example, the host "bah.rochester.ny.us" is registered in the DNS with a pointer to the mail relay "relay1.uu.net". This type of pointer is called an MX record. This gives electronic mail users a uniform mail addressing syntax and avoids making users aware of the underlying network boundaries. The reason for the development of the domain system was growth in the Internet. The hostname to address mappings were maintained by the InterNIC in a single file, called HOSTS.TXT, which was FTP'd by all the hosts on the Internet. The network population was changing in character. The time-share hosts that made up the original ARPANET were being replaced with local networks of workstations. Local organizations were administering their own names and addresses, but Cooper & Postel [Page 2] RFC 1480 The US Domain June 1993 had to wait for the NIC to make changes in HOSTS.TXT to make the changes visible to the Internet at large. Organizations also wanted some local structure on the name space. The applications on the Internet were getting more sophisticated and creating a need for general purpose name service. The idea of a hierarchical name space, with the hierarchy roughly corresponding to organizational structure, and names using "." as the character to mark the boundary between hierarchy levels was developed. A design using a distributed database and generalized resources was implemented. The DNS provides standard formats for resource data, standard methods for querying the database, and standard methods for name servers to refresh local data from other name servers. 1.2 Top-Level Domains The top-level domains in the DNS are EDU, COM, GOV, MIL, ORG, INT, and NET, and all the 2-letter country codes from the list of countries in ISO-3166. The establishment of new top-level domains is managed by the Internet Assigned Numbers Authority (IANA). The IANA may be contacted at IANA@ISI.EDU. Even though the original intention was that any educational institution anywhere in the world could be registered under the EDU domain, in practice, it has turned out with few exceptions, only those in the United States have registered under EDU, similarly with COM (for commercial). In other countries, everything is registered under the 2-letter country code, often with some subdivision. For example, in Korea (KR) the second level names are AC for academic community, CO for commercial, GO for government, and RE for research. However, each country may go its own way about organizing its domain, and many have. There are no current plans of putting all of the organizational domains EDU, GOV, COM, etc., under US. These name tokens are not used in the US Domain to avoid confusion. Currently, only four year colleges and universities are being registered in the EDU domain. All other schools are being registered in the US Domain. There are also concerns about the size of the other top-level domains (especially COM) and ideas are being considered for restructuring. Other names sometimes appear as top-level domain names. Some people have made up names in the DNS-style without coordinating or registering with the DNS management. Some names that typically appear are BITNET, UUCP, and two-letter codes for continents, such as Cooper & Postel [Page 3] RFC 1480 The US Domain June 1993 "NA" for North America (this conflicts with the official Internet code for Namibia). For example, the DNS-style name "KA7EEJ.CO.USA.NA" is used in the amateur radio network. These addresses are never supposed to show up on the Internet but they do occasionally. The amateur radio network people created their own naming scheme, and it interferes sometimes with Internet addresses. 1.3 The US Domain The US Domain is an official top-level domain in the DNS of the Internet community. The domain administrators are Jon Postel and Ann Westine Cooper at the Information Sciences Institute of the University of Southern California (USC-ISI). US is the ISO-3166 2-letter country code for the United States and thus the US Domain is established as a top-level domain and registered with the InterNIC the same way other country domains are. Because organizations in the United States have registered primarily in the EDU and COM domains, little use was initially made of the US domain. In the past, the computers registered in the US Domain were primarily owned by small companies or individuals with computers at home. However, the US Domain has grown and currently registers hosts in federal government agencies, state government agencies, K12 schools, community colleges, technical/vocational schools, private schools, libraries, city and county government agencies, to name a few. Initially, the administration of the US Domain was managed solely by the Domain Registrar. However, due to the increase in registrations, administration of subdomains is being delegated to others. Any computer in the United States may be registered in the US Domain. 2. NAMING STRUCTURE The US Domain hierarchy is based on political geography. The basic name space under US is the state name space, then the "locality" name space, (like a city, or county) then organization or computer name and so on. For example: BERKELEY.CA.US PORTLAND.WA.US Cooper & Postel [Page 4] RFC 1480 The US Domain June 1993 There is of course no problem with running out of names. The things that are named are individual computers. If you register now in one city and then move, the database can be updated with a new name in your new city, and a pointer can be set up from your old name to your new name. This type of pointer is called a CNAME record. The use of unregistered names is not effective and causes problems for other users. Inventing your own name and using it without registering is not a good idea. In addition to strictly geographically names, some special names are used, such as FED, STATE, AGENCY, DISTRICT, K12, LIB, CC, CITY, and COUNTY. Several new name spaces have been created, DNI, GEN, and TEC, and a minor change under the "locality" name space was made to the existing CITY and COUNTY subdomains by abbreviating them to CI and CO. A detailed description follows. Below US, Parallel to States: ----------------------------- "FED" - This branch may be used for agencies of the federal government. For example: ..FED.US "DNI" - DISTRIBUTED NATIONAL INSTITUTES - The "DNI" branch was created directly under the top-level US. This branch is to be used for distributed national institutes; organizations that span state, regional, and other organizational boundaries; that are national in scope, and have distributed facilities. For example: .DNI.US. Name Space Within States: ------------------------ "locality" - cities, counties, parishes, and townships. Subdomains under the "locality" would be like CI...US, CO...US, or businesses. For example: Petville.Marvista.CA.US. "CI" - This branch is used for city government agencies and is a subdomain under the "locality" name (like Los Angeles). For example: Fire-Dept.CI.Los-Angeles.CA.US. "CO" - This branch is used for county government agencies and is a subdomain under the "locality" name (like Los Angeles). For example: Fire-Dept.CO.San-Diego.CA.US. Cooper & Postel [Page 5] RFC 1480 The US Domain June 1993 "K12" - This branch may be used for public school districts. A special name "PVT" can be used in the place of a school district name for private schools. For example: .K12..US and .PVT.K12..US. "CC" - COMMUNITY COLLEGES - This branch was established for all state wide community colleges. For example: .CC..US. "TEC" - TECHNICAL AND VOCATIONAL SCHOOLS - The branch "TEC" was established for technical and vocational schools and colleges. For example: .TEC..US. "LIB" - LIBRARIES (STATE, REGIONAL, CITY, COUNTY) - This branch may be used for libraries only. For example: .LIB..US. "STATE" - This branch may be used for state government agencies. For example: .STATE..US. "GEN" - GENERAL INDEPENDENT ENTITY - This branch is for the things that don't fit easily into any other structure listed -- things that might fit in to something like ORG at the top-level. It is best not to use the same keywords (ORG, EDU, COM, etc.) that are used at the top-level to avoid confusion. GEN would be used for such things as, state-wide organizations, clubs, or domain parks. For example: .GEN..US. ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ VIEW OF SECOND LEVEL DOMAINS UNDER US +-------+ | US | +-------+ | +----------------------------------+ | | | | | +-----+ +-----+ +-----+ +-----+ +-----+ | FED | | DNI | | TX | | SD | | CA | +-----+ +-----+ +-----+ +-----+ +-----+ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Cooper & Postel [Page 6] RFC 1480 The US Domain June 1993 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ SCHOOL AND LIBRARY VIEW +-----+ | CA | +-----+ | +------------------------------------------------+ | | | | | +-----+ +-----+ +-----+ +-------------+ +-----+ | K12 | | CC | | TEC | | LOS ANGELES | | LIB | +-----+ +-----+ +-----+ +-------------+ +-----+ / /| /| /| /| +--------+ +---+ +---+ +--------+ +----------+ +------+ |sch dist| |PVT| |SJC| |WM TRADE| |pvt school| |MALIBU| +--------+ +---+ +---+ +--------+ +----------+ +------+ /| /| +--------+ +--------+ |sch name| |sch name| +--------+ +--------+ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ VIEW OF STATE, REGIONAL, and GENERAL AGENCIES +-----+ | CA | +-----+ | +-------------------------+ | | | +-------+ +--------+ +-----+ | STATE | |DISTRICT| | GEN | +-------+ +--------+ +-----+ /| /| /| +--------+ +------+ +---------+ |CALTRANS| |SCAQMD| |domain pk| ---------+ +------+ +---------+ | +--------+ |TCEW100E| +--------+ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Cooper & Postel [Page 7] RFC 1480 The US Domain June 1993 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ VIEW OF LOCALITY +-----+ | CA | +-----+ | +-----------------------------------+ | | +-------------------------+ +----------------+ | LOS ANGELES | | SANTA MONICA | +-------------------------+ +----------------+ / | | /| | /| / | | | | | +---+ +--+ +--+ +-----------+ +--+ +---+ |bus| |CI| |CO| | pvt school| |CI| |bus| +---+ +--+ +--+ +-----------+ +--+ +---+ / | | / | +------------+ / | |HARBOR GUARD| / | +------------+ +-----+ +-----+ +-----+ +----+ |FIRE | |ADMIN| |PARKS| |FIRE| +-----+ +-----+ +-----+ +----+ ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 2.1 State Codes The state codes are the two letter US Postal abbreviations. For example: "CA" California. 2.2 Locality Names Within the state name space there are "locality" names, some may be cities, some may be counties, some may be local names, but not incorporated entities. Registered names under "locality" could be like: .CI...US ==> city gov't agency .CO...US, ==> county gov't agency ...US ==> businesses In the cases where the locality name is a county, there is a branch under the locality name, called "county" or "CO", that is used by the county government. Businesses are registered directly under the locality name. Cooper & Postel [Page 8] RFC 1480 The US Domain June 1993 Under the city locality name space there is a "city" or "CI" branch for city government agencies. As usual, businesses and private schools may register directly under the city name. In the case where there is both a county and a city with the same locality name there is no problem, since the names will be unique with the "CO" or "CI" keyword. In our area the county has a fire department and the city has its own fire department. They could have names like: Fire-Dept.CI.Los-Angeles.CA.US Fire-Dept.CO.Los-Angeles.CA.US Cities may be named (designated) by their full name (spelled out with hyphens replacing spaces (e.g., Los-Angeles or Fort-Collins), or by a city code. The first choice is the full city name. In some cases it may be appropriate to use the well-known city abbreviation known throughout a locality. However, it is very desirable that all users in the same city use the same designator for the city. That is, any particular locality should have just one DNS name. Some users would like names associated with a greater metropolitan area or region like the "Bay Area" or "Tri-Cities". One problem with this is that these names are not necessarily unique within a state. The best thing to do in this case is to use the larger metropolitan city in your hostname. Cities and counties are used. Should all the names be obvious? Trying to do this is desirable and also impossible. There will come a point when the obviously right name for an organization is already taken. As the system grows this will happen with increasing frequency. While ease of use to the end user is desirable, a higher priority must be placed on having a system that operates. This means that the manageability of the system must have high consideration. The reason the DNS was created was to subdivide the problem of maintaining a list of hosts in the Internet into manageable portions. The happy result is that this subdivision makes name uniqueness easier and promotes logical grouping. What is a "logical grouping" though, always depends on the viewer. Many levels of delegation are needed to keep the zone files manageable. Many sections of the name space are needed to allow unique names to be easily added. Cooper & Postel [Page 9] RFC 1480 The US Domain June 1993 Way back in the olden days, when the Internet was invented, some thought that an 8-bit network number would be more than enough to number all the networks that would ever exist. Today, there are over 10,000 networks operating in the Internet, and arguments are made about the doubling time being 2 years versus 4 years. One concern is that things will continue to grow dramatically, and this will require more subdivision of the domain name management. Maybe the plan for the US Domain is overkill on growth planning, but there has never been overplanning for growth yet. When things are bigger, names have to be longer. There is an argument that with only 8-character names, and in each position allow a-z, 0-9, and -, you get 37**8 = 3,512,479,453,921 or 3.5 trillion possible names. It is a great argument, but how many of us want names like "xs4gp-7q". It is like license plate numbers, sure some people get the name they want on a vanity plate, but a lot more people who want something specific on a vanity plate can't get it because someone else got it first. Structure and longer names also let more people get their "obviously right" name. 2.3 Schools [...] 1. Name Uniqueness: [...] 2. Database Management: [...] Special Schools and Service Units [...] "PVT" Private Schools [...] Community Colleges and Technical Schools [...] 2.4 State Agencies [...] 2.5 Federal Agencies [...] 2.6 Distributed National Institutes [...] 2.7 General Independent Entities This name space was created for organizations that don't really fit anywhere else, such as state-wide associations, clubs, and "domain parks". Think of this as the miscellaneous category. The examples are state-wide clubs. For example, the Garden Club of Arizona, might want to be "GARDEN.GEN.AZ.US". Such a club has membership from all over the state and is not associated with any one city (or locality). Another example is "domain parks" that have been established up-to-now as entities in ORG. For example, there is "LONESTAR.ORG", which is a kind of computer club in Texas that has lots of dial-in computers registered. In the US Domain such an entity might have a name like "LONESTAR.GEN.TX.US". The organizations registered in GEN may typically be non-profit entities. These organizations don't fit in a and are not a school, library, or state agency. Ordinary businesses are not registered in GEN. Some suggest that these kinds of organizations are just like all the other things and ought to be registered under some . This may be true, but sometimes one just can't find any way to convince the applicant that it is the right thing to do. One can argue that any organization has to have a headquarters, or an office, or something about it that is in a fixed place, and thus the organization could be registered in that place. Some suggest that no token is needed, these entities could be directly under the . The problem with not having a token, is that you can't delegate the responsibility for registering these entities to someone separate from whoever is responsible for the . You want to be able to delegate for both name- uniqueness reasons, and operational management reasons. Having a token there makes both easy. Cooper & Postel [Page 16] RFC 1480 The US Domain June 1993 General Independent Entities: ----------------------------- CAL-Comp-Club.GEN.CA.US <==== The Computer Club of California 2.8 Examples of Names For small entities like individuals or small businesses, there is usually no problem with selecting locality based names. For example: Zuckys.Santa-Monica.CA.US For large entities like large corporations with multiple facilities in several cities or states this often seems like an unreasonable constraint (especially when compared with the alternative of registering directly in the COM domain). However, a company does have a headquarters office in a particular locality and so could register with that name. Example: IBM.Armonk.NY.US PRIVATE (business or individual) ================================ Camp-Curry.Yosemite.CA.US <==== a business IBM.Armonk.NY.US <==== a business Dogwood.atl.GA.US <==== a business Geo-Petrellis.Culver-City.CA.US <==== a restaurant Zuckys.Santa-Monica.CA.US <==== a restaurant Joe-Josts.Long-Beach.CA.US <==== a bar Holodek.Santa-Cruz.CA.US <==== a personal computer FEDERAL ======= Senate.FED.US <==== US Senate DOD.FED.US <==== US Defense Dept. DOT.FED.US <==== US Transportation Dept. USPS.FED.US <==== US Postal Service VA.FED.US <==== US Veterans Administration IRS.FED.US <==== US Internal Revenue Service Yosemite.NPS.Interior.FED.US <==== a federal agency MNPL.FRB.FED.US. <==== US Fed. Reserve Bank of Minneapolis Cooper & Postel [Page 17] RFC 1480 The US Domain June 1993 STATE ===== Senate.STATE.MN.US <==== state Senate House.STATE.MN.US <==== state House of Reps MDH.STATE.MN.US <==== state Health Dept. HUD.STATE.CA.US <==== state House and Urban Dev. Dept. DOT.STATE.MN.US <==== state Transportation Dept. CALTRANS.STATE.CA.US <==== state Transportation Dept. DMV.STATE.CA.US <==== state Motor Vehicles Dept. Culver-City.DMV.STATE.CA.US <==== a local office of DMV DNI (distributed national Institutes) ====================================== METACENTER.DNI.US <==== a distributed nat'l Inst. GEN (General Independent Entities) ================================== GARDEN.GEN.AZ.US <==== a garden club of Arizona CITY | CI | COUNTY | CO (locality) ================================== Parks.CI.Culver-City.CA.US <==== a city department Fire-Dept.CI.Los-Angeles.CA.US <==== a city department Fire-Dept.CO.Los-Angeles.CA.US <==== a county department Planning.CO.Fulton.GA.US. <==== a county department Main.Library.CI.Los-Angeles.CA.US <==== a city department MDR.Library.CO.Los-Angeles.CA.US <==== a county department TOWNSHIP | PARISH (locality) ============================ Police.TOWNSHIP.Green.OH.US <==== a township department Administration.PARISH.Lafayette.LA.US <==== a parish department Cooper & Postel [Page 18] RFC 1480 The US Domain June 1993 DISTRICT | LIBRARY (agency) ============================ SCAQMD.DISTRICT.CA.US <==== a regional district Bunker-Hill-Improvement.DISTRICT.LA.CA.US <==== a local district Huntington.LIB.CA.US <==== a private library Venice.LA-City.LIB.CA.US <==== a city library MDR.LA-County.LIB.CA.US <==== a county library K12 | PRIVATE SCHOOLS (PVT) | CC | TEC ====================================== Hamilton.High.LA-Unified.K12.CA.US <==== a public school Sherman-Oaks.Elem.LA-Unified.K12.CA.US <==== a public K12 school John-Muir.Middle.Santa-Monica.K12.CA.US <==== a public K12 school Culver-High.CCSD.K12.CA.US <==== a public K12 school St-Monica.High.Santa-Monica.CA.US <==== a private school Crossroads-School.Santa-Monica.CA.US <==== a private school Mary-Ellens.Montessori-School.LA.CA.US <==== a private school Progress-Learning-Center.PVT.K12.CA.US <==== a private school SMCC.Santa-Monica.CC.CA.US <==== a public community college Trade-Tech.Los-Angeles.CC.CA.US <==== a public community college Valley.Los-Angeles.CC.CA.US <==== a public community college Brick-and-Basket-Institute.TEC.CA.US <== a technical college When appropriate, subdomains are delegated and partioned in various categories, such as: ..US = city/locality based names K12..US = kindergarten thru 12th grade PVT.K12..US = community colleges TEC..US = technical or vocational schools LIB..US = libraries STATE..US = state government agencies .FED.US = federal government agencies .DNI.US = distributed national institutes .GEN..US. = statewide assoc,clubs,domain parks The Appendix-I contains the current US Domain Names BNF. Cooper & Postel [Page 19] [...] ________________________________________________________________________________ no copyright 2000 rolux.org - no commercial use without permission. is a moderated mailing list for the advancement of minor criticism. post to the list: mailto:inbox@rolux.org. more information: mailto:minordomo@rolux.org, no subject line, message body: info rolux. further questions: mailto:rolux-owner@rolux.org. home: http://rolux.org/lists - archive: http://rolux.org/archive